Hong Life CalculatorsAll science & engineering tools
Mechanics
- Kinematics Calculator (SUVAT equations)
- Projectile Motion Calculator (range, max height, flight time)
- Free Fall Calculator (time, speed from height)
- Terminal Velocity Calculator (drag)
- Drag Force Calculator
- Force Calculator (F = ma) & Weight
- Friction Force Calculator
- Inclined Plane Calculator
- Pulley & Atwood Machine Calculator
- Momentum & Impulse Calculator
- Collision Calculator (elastic & inelastic, 1D)
- Kinetic & Potential Energy Calculator
- Work & Power Calculator
- Hooke’s Law & Spring Calculator
- Springs in Series & Parallel Calculator
- Circular Motion Calculator (centripetal force)
- Banked Curve Calculator (ideal bank angle)
- Torque & Lever Calculator
- Moment of Inertia Calculator (common shapes)
- Rotational Energy & Angular Momentum Calculator
- Pendulum Period Calculator
- Damped Oscillator & Resonance Calculator
- Gravitational Force Calculator (Newton)
- Escape & Orbital Velocity Calculator
- Kepler’s Third Law Calculator (period ⇄ semi-major axis)
- Geostationary & Synchronous Orbit Calculator
- Rocket Equation Calculator (Tsiolkovsky Δv)
- Density, Mass & Volume Calculator
- Fulcrum Calculator (where to put the pivot of a lever)
- Efficiency Calculator (useful output ÷ input, losses)
- Center of Mass Calculator (point masses in 1-D, 2-D or 3-D)
- Angle of Impact Calculator (bloodstain width ÷ length, educational)
- Car Crash Calculator (deceleration in g, impact force & fall-height equivalent)
- Newton's Third Law Calculator (action–reaction force, accelerations and speeds)
- Tension Calculator (load hung from two ropes, or a rope accelerating up/down)
- TNT Equivalent Calculator (joules ↔ tons, kilotons, megatons of TNT)
- Ballistic Coefficient Calculator (β = m / (C_D·A), drag deceleration, terminal velocity)
- Car Jump Distance Calculator (ramp speed & angle → jump length, speed to clear a gap)
- Resultant Velocity Calculator (add 2 or 3 velocity vectors: speed and direction)
- Rolling Resistance Calculator (force, power and energy from C_rr and vehicle mass)
- Sled Ride Calculator (speed at the bottom, time and run-out from slope and friction)
- Angular Acceleration Calculator (α from speed change and time, or torque and inertia)
- Angular Displacement Calculator (θ = ω₀t + ½αt², degrees and revolutions)
- Angular Frequency Calculator (ω = 2πf = 2π/T, spring–mass and pendulum)
- Flywheel Energy Storage Calculator (E = ½Iω², usable energy between two speeds)
- Harmonic Wave Equation Calculator (y(x,t) = A sin(kx − ωt + φ))
- Rotational Stiffness Calculator (k = M / θ, N·m/rad, torsional frequency)
- Simple Harmonic Motion Calculator (x, v and a at time t from amplitude and period)
- Car Center of Mass Calculator (CG position and height from axle-scale weights)
- Reduced Mass Calculator (μ = m₁m₂ / (m₁ + m₂) for two-body problems)
Fluids
- Hydrostatic Pressure Calculator
- Buoyancy Calculator (Archimedes)
- Hydraulic Press Calculator (Pascal’s law)
- Bernoulli Equation Calculator
- Continuity Equation & Pipe Flow Velocity
- Venturi Meter Flow Calculator
- Tank Drain Time Calculator (Torricelli)
- Pitot Tube Airspeed Calculator
- Reynolds Number Calculator
- Pipe Pressure Drop Calculator (Darcy-Weisbach, Colebrook)
- Hagen-Poiseuille Laminar Flow Calculator
- Stokes’ Law Settling Velocity Calculator
- Water Hammer Pressure Surge Calculator (Joukowsky)
- Capillary Rise Calculator (Jurin’s law)
- Specific Gravity Calculator (relative density & API gravity)
- PSI to GPM Calculator (flow from nozzle pressure and diameter)
- Coefficient of Discharge Calculator (Cd = actual ÷ theoretical flow)
- Valve Cv Calculator (flow coefficient Cv/Kv, flow rate or pressure drop for liquids)
- Differential Pressure Calculator (Δp between two points, U-tube manometer, √Δp flow)
- Hydraulic Gradient Calculator (i = Δh/L, flow direction and critical gradient)
- Lift Coefficient Calculator (CL from lift, speed, density and wing area)
- Magnus Force Calculator (sideways force on a spinning ball)
- Manometer Calculator (U-tube and inclined manometer pressure)
- Oblique Shock Calculator (θ–β–M: shock angle, M₂ and pressure ratios)
- Prandtl–Meyer Expansion Calculator (supersonic turn: ν, M₂, p₂/p₁)
- Water Density Calculator (density of pure water by temperature, 0–40 °C)
- Water Viscosity Calculator (dynamic and kinematic viscosity by temperature)
- Y+ Calculator (first cell height for a CFD mesh)
- NPSH Calculator (net positive suction head available vs required)
Waves & sound
- Wave Speed, Frequency & Wavelength Calculator
- Speed of Sound Calculator (air temperature)
- Doppler Effect Calculator (sound)
- Decibel Calculator (add dB levels, ratio ⇄ dB)
- Sound Level vs Distance Calculator (inverse square)
- Beat Frequency Calculator
- String Vibration & Standing Wave Calculator
- Open & Closed Pipe Resonance Calculator
- Harmonic Series Calculator (overtone frequencies and nearest notes)
- Acoustic Impedance Calculator (Z = ρc, reflection and transmission at a boundary)
- Alfvén Velocity Calculator (MHD wave speed v_A = B/√(μ₀ρ) in a plasma)
- Speed of Sound in Solids Calculator (longitudinal, bar and shear waves)
Electrical & electronics
- Ohm’s Law Calculator (V, I, R, P)
- Resistors in Series & Parallel Calculator
- Resistor Color Code Calculator (4 & 5 band)
- Voltage Divider Calculator
- Current Divider Calculator
- Wire Resistance & Voltage Drop Calculator
- Wheatstone Bridge Calculator
- Thévenin ⇄ Norton & Max Power Transfer Calculator
- Delta (Δ) ⇄ Wye (Y) Conversion Calculator
- Capacitors in Series & Parallel + Energy Calculator
- Inductors in Series & Parallel + Energy Calculator
- RC Time Constant & Charging Calculator
- RL Time Constant Calculator
- RLC Resonant Frequency & Q Calculator
- Reactance & Impedance Calculator
- RMS, Peak & Average Voltage Calculator
- AC Power Calculator (real, reactive, apparent, PF)
- Power Factor Correction Capacitor Calculator
- Three-Phase Power Calculator
- Transformer Turns Ratio Calculator
- Coulomb’s Law & Electric Field Calculator
- Solenoid & Wire Magnetic Field Calculator
- Lorentz Force Calculator (charge & wire)
- Faraday’s Law Induced EMF Calculator
- Skin Depth Calculator
- Coaxial Cable Impedance Calculator
- Microstrip Impedance Calculator (PCB trace)
- VSWR, Return Loss & Reflection Coefficient Calculator
- dBm ⇄ Watts ⇄ dBW Converter
- Free Space Path Loss Calculator & Link Budget
- Antenna Length Calculator (dipole, quarter-wave)
- LED Series Resistor Calculator
- Zener Diode Regulator Calculator
- BJT Transistor Switch & Bias Calculator
- MOSFET Conduction Loss & Heatsink Calculator
- Op-Amp Gain Calculator (inverting, non-inverting, summing, differential)
- 555 Timer Calculator (astable & monostable)
- RC Low-Pass & High-Pass Filter Calculator
- Sallen-Key 2nd-Order Low-Pass Filter Calculator
- Buck Converter Calculator (duty, inductor, ripple)
- Boost Converter Calculator
- Linear Regulator (LDO) Power & Temperature Calculator
- Battery Life Calculator (mAh & load)
- Battery Energy (Wh) & C-Rate Calculator
- Electrical Energy & Charge Calculator (kWh, J, C)
- HP to Amps Calculator (motor current from horsepower, DC, 1-phase & 3-phase)
- Breaker Size Calculator (US NEC 125% rule & standard ampere ratings)
- Joules to Volts Calculator (V = energy ÷ charge, coulombs, mAh or electrons)
- RMS to Watts Converter (amplifier power from RMS voltage and speaker impedance)
- Duty Cycle Calculator (% from pulse width and period, frequency or OFF time)
- Impedance Matching Calculator (L-network inductor and capacitor values)
- LM317 Calculator (output voltage from R1 and R2, R2 for a target voltage)
- PCB Trace Resistance Calculator (copper track resistance, voltage drop and loss)
- Pi Attenuator Calculator (π-pad resistor values from dB and impedance, plus T-pad)
- Acceleration in an Electric Field Calculator (a = qE/m for electrons, protons, ions)
- Cyclotron Frequency Calculator (f = qB/2πm, period and orbit radius)
- Debye Length Calculator (plasma screening length, Debye number and plasma frequency)
- Electric Dipole Moment Calculator (p = qd in C·m and debye, torque and energy in a field)
- Drift Velocity Calculator (electron speed in a wire, v = I/nqA)
- Electric Motor Torque Calculator (from voltage, current, efficiency and rpm)
- Electric Potential Calculator (V = kQ/r of a point charge, potential energy qV)
- Energy Density of Electric and Magnetic Fields Calculator (½ε₀E² + B²/2μ₀)
- Excess Electrons Calculator (how many electrons make a charge, N = Q/e)
- Frequency Bandwidth Calculator (−3 dB bandwidth from Q, or Q from the cut-off frequencies)
- Gauss’s Law Calculator (electric field of a charged sphere, shell, line or sheet)
- Hall Coefficient Calculator (R_H = 1/nq, carrier density from Hall voltage)
- Insertion Loss Calculator (dB loss of a cable, filter or connector from power or voltage)
- Internal Resistance Calculator (battery r from open-circuit and loaded voltage)
- Magnetic Dipole Moment Calculator (μ = N·I·A, torque and energy in a field)
- Magnetic Permeability Calculator (μ = μ₀μr, relative permeability and susceptibility)
- Bridge Rectifier Calculator (DC output voltage, ripple and diode ratings)
- Capacitive Transformerless Power Supply Calculator (C1, current and R1, AN954)
- Flyback Converter Calculator (duty cycle, turns ratio, peak current, CCM/DCM)
- Forward Converter Calculator (duty cycle, reset limit, output inductor ripple)
- Helical Coil Calculator (wire length, pitch, height and helix angle)
- MOSFET Threshold Voltage Calculator (VT from doping, oxide thickness, gate and body bias)
- Force Between Parallel Wires Calculator (F/L = μ₀I₁I₂ ÷ 2πd)
- SiPM Photon Detection Efficiency Calculator (PDE = FF × QE × Pt)
- Shockley Diode Equation Calculator (I = Is(e^(V/nVT) − 1), current or voltage)
- Solenoid Inductance Calculator (L = μ₀μrN²A/l, with Wheeler short-coil estimate)
- Voltage Regulation Calculator (no-load vs full-load, transformer %R and %X)
- Intrinsic Carrier Concentration Calculator (nᵢ vs temperature, silicon or custom)
- EIRP Calculator (effective isotropic radiated power, dBm, W and ERP)
- Voltage Drop Calculator (IEC 60364-5-52 method)
- Wire Size Calculator (minimum cross-section by voltage drop)
Thermodynamics & heat
- Temperature Converter (°C, °F, K, °R)
- Heat Energy Calculator (Q = mcΔT)
- Latent Heat Calculator (melting & boiling)
- Water Heating Time & Cost Calculator
- Mixing Temperature Calculator (final temperature)
- Thermal Expansion Calculator (linear & volume)
- Ideal Gas Law Calculator (PV = nRT)
- Combined Gas Law Calculator (Boyle, Charles, Gay-Lussac)
- Van der Waals Real Gas Calculator
- Partial Pressure Calculator (Dalton’s law)
- Graham’s Law of Effusion Calculator
- Adiabatic & Isothermal Process Calculator
- Carnot Efficiency & COP Calculator
- Heat Pump COP & Running Cost Calculator
- Otto & Diesel Cycle Efficiency Calculator
- Brayton Cycle (Gas Turbine) Efficiency Calculator
- Entropy Change Calculator
- Gibbs Free Energy Calculator
- Clausius-Clapeyron Vapour Pressure Calculator
- Boiling Point at Altitude Calculator (water)
- Antoine Equation Vapour Pressure Calculator
- Boltzmann Factor Calculator (e^(−ΔE/kT) and population ratio)
- Compressibility Factor Calculator (Z = PV/nRT, real vs ideal gas)
- Curie’s Law Calculator (paramagnetic susceptibility χ = C/T and magnetization)
- Electrical Mobility Calculator (μ = v_d/E, from conductivity or Einstein relation)
- Isentropic Flow Calculator (p/p₀, T/T₀, ρ/ρ₀ and A/A* from Mach number)
- Joule Heating Calculator (heat from current: Q = I²Rt, Wh and temperature rise)
- Mean Free Path Calculator (gas molecules: λ = kT/(√2·π·d²·p))
- Specific Gas Constant Calculator (R = Rᵤ/M for air, CO₂, steam and more)
- Thermal Diffusivity Calculator (α = k/(ρ·cₚ), m²/s and heating time)
Heat transfer
- Heat Conduction Calculator (Fourier’s law)
- U-Value Calculator (wall layers)
- Convection Heat Transfer Calculator (Newton’s cooling)
- Newton’s Law of Cooling Calculator (temperature over time)
- Thermal Radiation Calculator (Stefan-Boltzmann)
- LMTD Heat Exchanger Calculator
- Heat Exchanger ε-NTU Calculator
- Straight Fin Efficiency Calculator
- Dimensionless Numbers Calculator (Nu, Pr, Bi, Fo)
- Dew Point & Relative Humidity Calculator (Magnus)
- Relative Humidity from Dew Point
- Wet-Bulb Temperature Calculator (Stull)
- Evaporative Cooler Outlet Temperature Calculator
- Diffusion Calculator (Fick’s law, diffusion length)
- Room Cooling Load (BTU) Estimator
Mechanical & structural
- Stress, Strain & Young’s Modulus Calculator
- Axial Deformation Calculator (PL/AE)
- Section Properties Calculator (rectangle, circle, tube, I-beam)
- Beam Deflection & Bending Calculator (simply supported & cantilever)
- Shaft Torsion Calculator (stress & twist)
- Power ⇄ Torque ⇄ RPM Calculator
- Column Buckling Calculator (Euler)
- Von Mises & Principal Stress Calculator (Mohr’s circle)
- Fatigue Safety Factor Calculator (Goodman, Soderberg)
- Miner’s Rule Cumulative Fatigue Damage Calculator
- Stress Concentration (hole in plate) Calculator
- Thin-Wall Pressure Vessel Stress Calculator
- Bolt Tensile Stress Area & Shear Calculator
- Fillet Weld Strength Calculator
- Gear Ratio, Speed & Module Calculator
- Belt Length & Pulley Speed Calculator
- Roller Chain Length Calculator (links)
- Bearing L10 Life Calculator
- Hydraulic Cylinder Force & Speed Calculator
- Pump Power Calculator (hydraulic & water)
- Helical Compression Spring Calculator
- Bolt Torque Calculator (metric bolts, T = K·F·d)
- Linear Actuator Force Calculator (push force for a load on a slope)
- Mechanical Advantage Calculator (lever, wheel and axle, pulley, ramp, screw)
- Torsion Spring Calculator (torque, spring rate & bending stress)
- Wing Loading Calculator (kg/m², lb/ft² and stall speed)
- Angle of Repose Calculator (from pile height and base radius)
- Brinell Hardness Calculator (HBW from force, ball and indentation)
- Bulk Modulus Calculator (K = −Δp ÷ ΔV/V₀, compressibility)
- Elastic Constants Calculator (E, G, ν, K and Lamé λ from any two)
- Factor of Safety Calculator (FoS, margin of safety, allowable stress)
- Impact Test Calculator (Charpy / Izod pendulum absorbed energy)
- Mohr's Circle Calculator (stress on a plane rotated by any angle θ)
- Natural Frequency Calculator (fₙ from stiffness & mass or static deflection)
- Number Density Calculator (particles per m³ from count, density or gas pressure)
- Poisson's Ratio Calculator (from length and width changes)
- Shear Modulus Calculator (G = τ/γ, or from E and ν)
- Shear Wave Velocity Calculator (Vs = √(G/ρ), Vp and small-strain G)
- Slenderness Ratio Calculator (KL/r from section shape, Euler vs Johnson)
- Stiffness Matrix Calculator (2-D truss bar element, global 4×4 matrix)
- Torsional Constant Calculator (J for round, tube, rectangle, box and open sections)
- Vickers Hardness Calculator (HV from force and indentation diagonals)
Civil & geotechnical
- Concrete Mix Quantities Calculator (by ratio)
- Soil Effective Stress Calculator
- Bearing Capacity Calculator (Terzaghi equation with Vesic factors, strip footing)
- Lateral Earth Pressure Calculator (Rankine)
- Infinite Slope Stability Calculator
- Consolidation Settlement Calculator
- Darcy’s Law Seepage Calculator
- Manning’s Equation Open Channel Flow Calculator
- Gravity Pipe Full-Flow Capacity Calculator
- Hydraulic Jump Calculator
- Weir Flow Calculator (rectangular & V-notch)
- Peak Runoff Calculator (Rational Method)
- SCS Curve Number Runoff Calculator
- Time of Concentration Calculator (Kirpich)
- Stopping Sight Distance Calculator
- Road Superelevation & Minimum Radius Calculator
- Vertical Curve Calculator (crest & sag)
- Earthwork Volume Calculator (average end area & prismoidal)
- Reinforced Concrete Beam Moment Capacity (rectangular, singly reinforced)
- Concrete Rebound Hammer Strength Estimator
- Fire Flow Calculator (Iowa rate-of-flow and NFA formulas for the fireground)
Chemistry
- Molar Mass Calculator (chemical formula)
- Grams ⇄ Moles ⇄ Particles Converter
- Molarity Calculator (mass for a solution)
- Concentration Converter (M, % w/v, mg/mL, ppm, normality)
- Dilution Calculator (C1V1 = C2V2)
- Serial Dilution Calculator
- Concentrated Acid Molarity Calculator (from % and density)
- pH Calculator (strong & weak acids/bases)
- Buffer pH Calculator (Henderson-Hasselbalch)
- Titration Calculator (unknown concentration)
- Ksp Solubility Calculator
- Limiting Reactant & Theoretical Yield Calculator
- Empirical Formula Calculator (from mass %)
- Colligative Properties Calculator (boiling, freezing, osmotic pressure)
- Ionic Strength Calculator
- Arrhenius Equation & Q10 Calculator
- Reaction Kinetics & Half-Life Calculator (0, 1st, 2nd order)
- Nernst Equation Calculator
- Electrolysis & Electroplating Calculator (Faraday)
- Beer-Lambert Law Calculator (absorbance ⇄ concentration)
- Photon Energy & Wavelength Calculator
- Hydrogen Spectrum Calculator (Rydberg formula)
- De Broglie Wavelength Calculator
- Radioactive Decay & Half-Life Calculator
- Carbon-14 Dating Calculator
- Bragg’s Law & Scherrer Crystallite Size Calculator
- Reaction Enthalpy from Formation Enthalpies (Hess)
- Equilibrium Constant & Kp ⇄ Kc Calculator
- Gas Density Calculator
- Gas Volume at STP / NTP Calculator
- Chemical Equation Balancer (smallest whole-number coefficients)
- Electron Configuration Calculator (all elements 1–108, NIST ground states)
- Molar Ratio Calculator (mole ratio from coefficients, moles and grams of product)
- Rate Constant Calculator (k from the rate law, two concentrations or half-life)
- Reaction Quotient Calculator (Q from concentrations, compare with K to find the direction)
- Gibbs Phase Rule Calculator (degrees of freedom F = C − P + 2)
- Q10 Calculator (temperature coefficient from two measured rates)
- Cell EMF Calculator (standard cell potential E°cell, ΔG° and K from half-reactions)
- Lattice Energy Calculator (Born–Landé and Kapustinskii equations)
- Atom Calculator (element, mass number and charge from protons, neutrons and electrons)
- Average Atomic Mass Calculator (from isotope masses and abundances)
- Bond Order Calculator (MO theory for H₂ to Ne₂ and ions, or your own electron counts)
- Effective Nuclear Charge Calculator (Zeff by Slater’s rules, elements 1–108)
- Electronegativity Calculator (Pauling values, Δχ and bond type for two elements)
- Percent Composition Calculator (mass % of each element and grams in a sample)
- Percent Ionic Character Calculator (Pauling, Hannay–Smyth and dipole-moment methods)
- pKa Calculator (Ka ⇄ pKa ⇄ pKb, and acid/base forms at any pH)
- Activity Coefficient Calculator (Debye–Hückel, extended DH and Davies equations)
- Alligation Calculator (mix two strengths to a target %: parts and amounts)
- Buffer Capacity Calculator (β from concentration, pKa and pH; base needed for a pH shift)
- Neutralization Calculator (volume or mass of base to neutralise an acid)
- Chemical Name Calculator (inorganic formula → IUPAC name: salts, acids, binary compounds)
- Net Ionic Equation Calculator (complete ionic equation and spectator ions)
- Raoult’s Law Calculator (vapor pressure of a solution with a nonvolatile solute)
- Saponification Value Calculator (lye for soap: NaOH or KOH from oil SAP values)
- TDS Calculator (total dissolved solids from electrical conductivity, EC → ppm)
- Chemical Oxygen Demand Calculator (COD in mg/L from dichromate titration)
- Combustion Analysis Calculator (empirical formula from CO₂ and H₂O masses)
- Crude Protein Calculator (nitrogen × 6.25 or Jones factor, Kjeldahl titration)
- Degree of Unsaturation Calculator (DBE, rings plus double bonds from a molecular formula)
- Liquid Ethylene Density Calculator (saturated liquid C₂H₄, 105–275 K)
- Cubic Cell Calculator (SC, BCC, FCC: edge length, atomic radius, density)
- Miller Indices Calculator (plane intercepts → (hkl) and cubic d-spacing)
- Osmotic Pressure Calculator (Π = iMRT, or molar mass from a measured Π)
- Young–Laplace Equation Calculator (pressure inside drops, bubbles and curved surfaces)
- Atom Economy Calculator (green chemistry: % of reactant atoms in the product)
- Avogadro’s Number Calculator (moles ⇄ particles ⇄ atoms ⇄ grams)
- Molality Calculator (mol of solute per kg of solvent)
- Mole Fraction Calculator (from moles or from grams and molar masses)
- Residence Time Calculator (τ = V ÷ Q for reactors, tanks and basins)
- Dimensional Analysis Calculator (factor-label unit conversion with unit cancelling)
Biology & lab
- DNA/RNA Concentration & Purity Calculator (A260)
- DNA Copy Number & pmol ⇄ ng Calculator
- Primer Tm & GC% Calculator
- Reverse Complement & Translation Tool
- Ligation Insert:Vector Ratio Calculator
- qPCR ΔΔCt Fold Change Calculator
- qPCR Efficiency from Standard Curve Slope
- Cell Doubling Time & Growth Rate Calculator
- Hemocytometer Cell Count & Viability Calculator
- Cell Seeding Calculator
- OD600 to Cell Density Calculator
- Centrifuge RCF ⇄ RPM Calculator
- Michaelis-Menten Enzyme Kinetics Calculator
- Hardy-Weinberg Equilibrium Calculator
- Punnett Square Calculator (monohybrid & dihybrid)
- Shannon & Simpson Diversity Index Calculator
- Sequencing Coverage Calculator (NGS)
- RPKM / FPKM / TPM Calculator
- Four-Parameter Logistic (IC50/EC50) Calculator
- MOI (Multiplicity of Infection) Calculator
- Protein Concentration from A280 Calculator
- Protein Extinction Coefficient & MW from Sequence
- Lab Buffer Recipe Calculator (PBS, TAE, TBE, TE)
- Agarose Gel Percentage & Recipe Calculator
- Hill Equation & Oxygen Saturation (P50) Calculator
- Bacterial Growth Calculator (generation time)
- Molecular Clock Divergence Time Calculator
- Effective Population Size (Ne) Calculator
- Water Potential Calculator (Ψ = Ψs + Ψp, solute potential −iCRT)
- Log Reduction Calculator (log kill ⇄ percent reduction ⇄ survivors)
- Allele Frequency Calculator (2 or 3 alleles from genotype counts, heterozygosity)
- Mutation Frequency Calculator (mutant frequency from selective and viable plate counts)
- Mutation Rate Calculator (fluctuation test: p₀ method & Lea–Coulson median)
- Trihybrid Cross Calculator (64-box Punnett square, AaBbCc phenotype ratio)
- Cricket Chirp Thermometer (Dolbear’s law: temperature from chirps)
- Rabbit Color Calculator (coat colour genetics: A, B, C, D, E loci)
- Calibration Curve Calculator (unknown concentration, uncertainty, LOD & LOQ)
- Enzyme Activity Calculator (U/mL and specific activity from ΔA/min)
- Isoelectric Point Calculator (protein or peptide pI from sequence, EMBOSS pKa set)
- Resuspension Calculator (oligo nmol → buffer volume for a target µM)
- SIR Model Calculator (epidemic peak, final size and herd immunity from R₀)
Environment
- BOD₅ Calculator (dilution method)
- Dissolved Oxygen Saturation Calculator
- Water Hardness Calculator (Ca, Mg → CaCO₃)
- Langelier Saturation Index (LSI) Calculator
- Activated Sludge Calculator (F/M, SRT, HRT, SVI)
- Disinfection CT Calculator
- Air Pollutant ppm ⇄ mg/m³ Converter
- Emission O₂ Reference Correction Calculator
- Air Quality Index (US EPA AQI) Calculator
- Fuel CO₂ Emissions Calculator
- Electricity CO₂ (Scope 2) Calculator
- CO₂ Equivalent (GWP) Calculator
- Biogas Methane from COD Calculator (anaerobic digester)
- Compost C:N Ratio Calculator
- RUSLE Soil Erosion Calculator
- Noise Barrier Insertion Loss Calculator (Maekawa)
- Reverberation Time Calculator (Sabine & Eyring)
- Chemical Exposure Dose & Hazard Quotient
- Streeter-Phelps DO Sag Calculator
- Normal ⇄ Actual Cubic Metre Converter (Nm³, Sm³, Am³)
- Lake Trophic State Index (Carlson) Calculator
- Tree Height Calculator (clinometer angles & distance)
- MLVSS Calculator (mixed liquor volatile suspended solids from filter weights or MLSS)
- Kaya Identity Calculator (CO₂ from population, GDP, energy and carbon intensity)
- Carrying Capacity Calculator (logistic K from growth rate or three counts)
- Lotka–Volterra Calculator (predator–prey populations, equilibrium and cycle length)
- Hydroelectric Power Calculator (P = η·ρ·g·Q·H, kW and annual energy)
- Wind Turbine Power Calculator (P = ½ρAv³Cp, Betz limit and tip speed ratio)
Astronomy & space
- Apparent ⇄ Absolute Magnitude & Distance Calculator
- Parallax Distance Calculator
- Magnitude Difference ⇄ Brightness Ratio (Pogson)
- Wien’s Law & Stefan-Boltzmann Star Calculator
- Hubble’s Law & Redshift Calculator
- Schwarzschild Radius & Time Dilation Calculator
- Roche Limit Calculator
- Hohmann Transfer Orbit Calculator
- Orbital Period & Speed Calculator (vis-viva)
- Planet Equilibrium Temperature Calculator
- Habitable Zone Calculator (simple)
- Drake Equation Calculator
- Julian Date & MJD Calculator
- Moon Phase Calculator
- Telescope Magnification, FOV & Resolution Calculator
- Astrophotography 500 & NPF Rule Calculator
- Sunrise & Sunset Calculator (NOAA algorithm)
- Sun Elevation Angle at Noon & Solar Declination
- Light Travel Time Calculator
- Impact Energy Calculator (asteroid)
- Kepler’s Equation Solver (mean → eccentric → true anomaly)
- Hill Sphere & Sphere of Influence Calculator
- Main-Sequence Lifetime Calculator
- Atmospheric Escape: Thermal Velocity vs Escape Velocity
- Age on Other Planets Calculator (your age in Mercury, Mars, Jupiter… years)
- Weight on Other Planets Calculator (Moon, Mars, Jupiter & more)
- Sidereal Time Calculator (local & Greenwich sidereal time from date, time, longitude)
- Exoplanet Transit Calculator (planet radius from transit depth)
- Specific Impulse Calculator (Isp from thrust & propellant flow)
- Synodic Period Calculator (time between alignments of two orbits)
- Black Hole Temperature Calculator (Hawking temperature from mass)
- Black Hole Collision Calculator (energy radiated in gravitational waves)
- Thrust to Weight Ratio Calculator (TWR for rockets, jets and drones)
- Radiation Pressure Calculator (light pressure, force and solar-sail acceleration)
Earth & weather
- Great-Circle Distance Calculator (Haversine)
- Barometric Altitude & ISA Atmosphere Calculator
- Heat Index Calculator (NWS)
- Wind Chill Calculator
- WBGT Heat Stress Calculator (estimated)
- Discomfort Index (Thom) Calculator
- Cloud Base (LCL) Calculator
- Earthquake Magnitude & Energy Calculator
- Moment Magnitude (Mw) Calculator
- Earthquake Distance from S−P Time Calculator
- Tsunami & Shallow Water Wave Speed Calculator
- Ocean Wave Calculator (period, wavelength, speed)
- Beaufort Wind Scale Converter
- Hurricane Category (Saffir-Simpson) Calculator
- Radiometric Rock Dating Calculator (K-Ar, U-Pb, Rb-Sr)
- Coriolis Parameter & Geostrophic Wind Calculator
- Foehn Wind Temperature Calculator
- Mixing Ratio & Specific Humidity Calculator
- Shaking Intensity from Peak Ground Acceleration (MMI)
- Antipode Calculator (opposite point on Earth from latitude & longitude)
- Lightning Distance Calculator (flash-to-thunder seconds to km & miles)
- Distance to Horizon Calculator (from eye height, with refraction)
- Earth Curvature Calculator (hidden height & drop over distance)
- Azimuth Calculator (initial and final bearing between two coordinates)
- Rain to Snow Calculator (liquid precipitation → snow depth by snow-to-liquid ratio)
- Rainfall Calculator (rainwater harvesting volume from roof area and rain)
- Vertical Exaggeration Calculator (topographic profile VE from map scales)
- Absolute Humidity Calculator (g/m³ of water vapor from temperature and RH)
- Psychrometric Calculator (dry-bulb and wet-bulb → RH, humidity ratio, enthalpy, dew point)
- SCFM Calculator (actual ACFM ⇄ standard cubic feet per minute)
- Temperature at Altitude Calculator (lapse rate: standard, dry adiabatic or custom)
- Virtual Temperature Calculator (Tv from temperature and mixing ratio, moist-air density)
- Magnetic Declination Calculator (WMM2025: true vs magnetic north by location and date)
Audio & signals
- Sound Frequency ⇄ Wavelength Calculator
- Room Modes Calculator (axial)
- Helmholtz Resonator / Bass Port Calculator
- dBu ⇄ dBV ⇄ Volts Converter
- Bit Depth, Sample Rate & Audio File Size Calculator
- MIDI Note ⇄ Frequency ⇄ Cents Calculator
- BPM to Delay & Reverb Time Calculator
- Passive Speaker Crossover Calculator (1st & 2nd order)
- Nyquist & Aliasing Frequency Calculator
- FFT Frequency Resolution Calculator
- SNR Calculator (power, voltage, dB)
- Loudness Normalisation Gain Calculator (LUFS)
- Octave & Third-Octave Band Frequency Calculator
- A- & C-Weighting Calculator (IEC 61672)
- Comb Filter & Speaker Delay Calculator
- Total Harmonic Distortion Calculator (THD % and dB from harmonic levels)
- Modulation Calculator (AM index & depth, FM index & Carson bandwidth)
- Noise Figure Calculator (NF from input & output SNR, noise temperature)
- Resistor Noise Calculator (Johnson–Nyquist thermal noise √4kTRB)
Quality & reliability
- Process Capability Calculator (Cp, Cpk, PPM)
- DPMO & Sigma Level Calculator
- Control Chart Limits Calculator (X̄-R)
- p-Chart Control Limits Calculator
- Weibull Reliability Calculator
- System Reliability Calculator (series, parallel, k-of-n)
- MTBF, MTTR & Availability Calculator
- Accelerated Life Test Factor Calculator (Arrhenius)
- FMEA Risk Priority Number Calculator
- Taguchi Loss Function Calculator
- Gage R&R Summary Calculator (% study variation)
- Acceptance Sampling OC Curve Calculator
- Rolled Throughput Yield Calculator
- CUSUM & EWMA Control Chart Calculator
- Error Propagation Calculator (uncertainty of sums, products, quotients and powers)
- Measurement Uncertainty Calculator (Type A from repeated readings + Type B, expanded U)
- Absolute Uncertainty Calculator (relative % ↔ absolute ± uncertainty)
Chemical engineering
- Distillation Minimum Stages (Fenske) & Gilliland Calculator
- Ideal VLE Calculator (Raoult’s law, relative volatility)
- Henry’s Law Gas Solubility Calculator
- Extraction / Stripping Stages Calculator (Kremser)
- Adsorption Isotherm Calculator (Langmuir & Freundlich)
- Reverse Osmosis Calculator (osmotic pressure, recovery, flux)
- Reactor Conversion Calculator (CSTR, PFR, batch, first & second order)
- Thiele Modulus & Catalyst Effectiveness Factor Calculator
- Minimum Fluidisation Velocity Calculator (Wen-Yu)
- Mixing Tank Agitator Power Calculator
- Combustion Air Calculator (CxHyOz fuel, excess air)
- Excess Air from Flue Gas O₂ Calculator
- Fuel Heating Value Calculator (Dulong, HHV ⇄ LHV)
- Mixture Flammability Limits (Le Chatelier) Calculator
- Cyclone Cut Size & Efficiency Calculator (Lapple)
- Grinding Energy Calculator (Bond’s law)
- Drying Time Calculator (constant & falling rate)
- Polymer Molecular Weight Calculator (Mn, Mw, PDI)
- Step-Growth Polymerisation (Carothers) Calculator
- Copolymer Glass Transition (Fox Equation)
- Mark-Houwink Intrinsic Viscosity Calculator
- Surfactant HLB Blend Calculator
- Power-Law Fluid Viscosity Calculator (shear thinning)
- Contact Angle, Work of Adhesion & Spreading Calculator
- Stokes-Einstein Particle Size from Diffusion (DLS)
- Surface Coverage & Gibbs Adsorption Calculator
- Heat Exchanger Duty & Area Calculator
- Liquid Leak Rate Through a Hole Calculator
- Mixing Material Balance Calculator (two streams)
- Evaporator Water Removal & Steam Economy Calculator
Optics & light
- Snell’s Law Calculator (refraction angle & critical angle)
- Thin Lens Equation Calculator (image distance & magnification)
- Inverse Square Law Calculator (intensity vs distance for light, sound, radiation)
- Watts to Lux Calculator (lamp power × lm/W → lumens → lux on an area or at a distance)
- Hair Diffraction Calculator (measure hair thickness with a laser pointer)
- Smartphone Projector Calculator (DIY box: lens focal length → box length and picture size)
- Angular Resolution Calculator (Rayleigh θ = 1.22 λ/D, smallest detail at a distance)
- Aperture Area Calculator (lens or mirror area, central obstruction, light-gathering power)
- Binoculars Range Calculator (distance from a mil-reticle reading and a known size)
- Brewster's Angle Calculator (polarizing angle θ_B = arctan(n₂/n₁))
- Diffraction Grating Calculator (angle of each order, d sin θ = mλ)
- Index of Refraction Calculator (n from speed, angles, critical angle or wavelength)
- Laser Beam Divergence Calculator (mrad from two beam diameters, M² estimate)
- Laser Beam Expander Calculator (Galilean & Keplerian, magnification and divergence)
- Laser Spot Size Calculator (focused Gaussian beam waist, Rayleigh range)
- Laser Brightness Calculator (radiance from power, wavelength and M²)
- Laser Linewidth & Bandwidth Calculator (Δλ ↔ Δν, coherence length)
- Lens Maker’s Equation Calculator (focal length from radii and refractive index)
- Malus’s Law Calculator (light through one or more polarizers, I = I₀ cos²θ)
- Mirror Equation Calculator (concave & convex mirrors, image distance and magnification)
- Optical Density Calculator (OD ↔ transmission %, stacked ND filters)
- Radar Horizon Calculator (4/3 Earth radius, antenna and target height)
- Thin-Film Optical Coating Calculator (quarter-wave anti-reflection layer)
Relativity & modern physics
- E = mc² Calculator (mass–energy equivalence: joules, kWh, TNT)
- Time Dilation Calculator (special relativity, Lorentz factor)
- Quantum Number Calculator (check n, l, mₗ, mₛ and count orbitals and electrons)
- Warp Speed Calculator (Star Trek warp factor to speed of light — fiction)
- Compton Scattering Calculator (wavelength shift and scattered photon energy)
- Compton Wavelength Calculator (h/mc for the electron, proton, neutron or any mass)
- Curie Constant Calculator (C = χT, effective magnetic moment and unpaired electrons)
- Fermi Level Calculator (free-electron Fermi energy, temperature and velocity of a metal)
- Heisenberg Uncertainty Principle Calculator (Δx·Δp ≥ ħ/2)
- Magnetic Moment Calculator (current loop, spin-only and orbital moments, torque)
- Photoelectric Effect Calculator (electron energy, stopping voltage, cut-off wavelength)
- Relativity Paradox Calculator (barn–pole and bug–rivet, length contraction)
- Electron Speed Calculator (from accelerating voltage, relativistic)
- Gravitational Time Dilation Calculator (clock rate near a planet, star or black hole)
- Length Contraction Calculator (relativistic L = L₀/γ)
- Relativistic Kinetic Energy Calculator (K = (γ − 1)mc² vs ½mv²)
- Space Travel Time Calculator (ship and Earth time, constant g or constant speed)
- Relativistic Velocity Addition Calculator (u = (v + u′)/(1 + vu′/c²))
Agriculture & forestry
- Acres per Hour Calculator (field capacity of farm machines, ha/h)
- Corn Yield Calculator (yield component method, bu/acre & t/ha)
- Daily Light Integral Calculator (DLI from PPFD & hours)
- GDU Calculator (growing degree units for corn, 86/50 °F method)
- Plant Population Calculator (plants per hectare & acre from row spacing)
- VPD Calculator (vapour pressure deficit from temperature & humidity)
- Cattle per Acre Calculator (stocking rate from forage yield & AUM)
- Basal Area Calculator (m²/ha & ft²/acre from tree diameters)
- Tree Age Calculator (estimate from trunk size & species growth factor)
- Tree Diameter Calculator (DBH from trunk circumference)
- Feed Conversion Ratio Calculator (FCR: kg feed per kg live-weight gain)
- Dry Matter Calculator (as-fed ↔ dry-matter basis for feed nutrients and amounts)
- Animal Mortality Rate Calculator (flock or herd mortality % and livability)
Automotive
- BSFC Calculator (brake specific fuel consumption, g/kWh & lb/hp·h)
- Boost Horsepower Calculator (turbo/supercharger power from boost & charge temperature)
- Compression Ratio Calculator (bore, stroke, chamber, gasket & piston volume)
- Compression Ratio to PSI Calculator (estimated cranking pressure, dynamic ratio)
- Fuel Injector Size Calculator (cc/min & lb/h from horsepower and BSFC)
- Fuel Pump Calculator (required pump flow in L/h & gal/h from horsepower)
- RPM Calculator (engine rpm from speed, gear ratio, final drive & tyre size)
- Speedometer Gear Calculator (driven-gear teeth after an axle-ratio or tyre change)
- Traffic Density Calculator (vehicles per km, flow, spacing & headway)
- Turbo Size Calculator (compressor airflow lb/min & pressure ratio for a target hp)
- BMEP Calculator (brake mean effective pressure from torque & displacement)
- Carburetor CFM Calculator (engine airflow from displacement, rpm & VE)
- Piston Speed Calculator (mean & peak piston speed from stroke, rpm & rod length)
Machining & manufacturing
- Carbon Equivalent Calculator (CE IIW, AWS, Pcm for steel weldability)
- K-Factor Calculator (sheet metal neutral axis from a test bend)
- Bend Allowance Calculator (sheet metal flat length, bend deduction)
- Material Removal Rate Calculator (MRR for milling, turning and drilling)
- Thread Pitch Diameter Calculator (ISO metric and Unified, 3-wire measurement)
- Punch Force Calculator (punching and blanking tonnage)
- Rivet Size Calculator (solid rivet diameter, length, edge distance and pitch)
- Spindle Speed Calculator (RPM from cutting speed and diameter)
- Speeds and Feeds Calculator (milling rpm, table feed, chip thinning)
- Taper Calculator (taper angle, ratio, taper per foot, tailstock set-over)
- True Position Calculator (GD&T position from X/Y deviation, with MMC bonus)
- Bolt Circle Calculator (PCD hole coordinates and spacing)
- Countersink Depth Calculator (depth from diameter and angle)
- Diametral Pitch Calculator (gear P, module, addendum, outside diameter)
FAQ
Can I use these for real designs?
They use standard textbook formulas for learning and quick estimates. Real structures, circuits and pressure systems must follow your local codes and be checked by a qualified engineer.
Checked 8 Nov 2026.