CGS System of Units Converter (dyne, erg, gauss, poise, stokes ↔ SI)

Understanding the CGS system of units converter — concept and principle

This converter changes values between centimetre–gram–second (CGS) units and their SI equivalents: dyne, erg, barye, gal, poise, stokes, gauss, maxwell, oersted, gilbert, stilb, phot and lambert. It works in both directions and shows the conversion factor and its inverse. Physics and engineering students, and anyone reading older scientific papers or magnet specifications, use it.

Gauss to tesla — with the default inputs: 0.5 T.

How it is calculated

CGS → SI: SI value = CGS value × factor; SI → CGS: CGS value = SI value ÷ factor
Mechanical units: 1 dyn = 10⁻⁵ N; 1 erg = 10⁻⁷ J; 1 erg/s = 10⁻⁷ W; 1 barye = 0.1 Pa; 1 dyn·cm = 10⁻⁷ N·m; 1 Gal = 0.01 m/s²
Viscosity: 1 P = 0.1 Pa·s; 1 St = 10⁻⁴ m²/s
Electromagnetic: 1 G = 10⁻⁴ T; 1 Mx = 10⁻⁸ Wb; 1 Oe = 1000/(4π) A/m ≈ 79.577 A/m; 1 Gb = 10/(4π) A ≈ 0.7958 A
Photometric: 1 sb = 10⁴ cd/m²; 1 ph = 10⁴ lx; 1 L = 10⁴/π cd/m²

The principle

The CGS system builds its units from the centimetre, the gram and the second, so most mechanical units are SI units scaled by a power of ten: a dyne is the force that accelerates one gram by one centimetre per second squared. The electromagnetic units come from the CGS (Gaussian) form of Maxwell's equations, which is why factors of 4π appear for the oersted and gilbert. Gauss measures magnetic flux density B, oersted measures field strength H; in empty space 1 G corresponds to 1 Oe, but they are different quantities.

Worked example

Default: 5,000 gauss, CGS → SI.

Factor: 1 G = 10⁻⁴ T.
SI value = 5,000 × 0.0001 = 0.5 T.
Value in CGS units: 5,000; value in SI units: 0.5.
Conversion factor: 1 G = 0.0001 T; inverse: 1 T = 10,000 G.

Each point is the calculator re-run with only “Value to convert” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Value to convert	Result
1,250	0.125 T
2,500	0.25 T
3,750	0.375 T
5,000	0.5 T
6,250	0.625 T
7,500	0.75 T
10,000	1 T

How to read the result

A field of 0.5 T is typical of a strong permanent magnet's surface field. Magnet and MRI specifications may be given in either unit, so converting to tesla makes them comparable. For viscosity, water at room temperature is about 1 centipoise, which is 1 mPa·s.

Common mistakes

Treating gauss and oersted as interchangeable inside magnetic materials.
Forgetting the 4π in oersted and gilbert conversions.
Confusing the gal (acceleration) with the gallon.
Mixing dynamic viscosity (poise) and kinematic viscosity (stokes).

Keep in mind: CGS electromagnetic units differ between the Gaussian, ESU and EMU variants. This converter uses the Gaussian/EMU magnetic units as listed in NIST SP 811.

Frequently asked questions

How many gauss are in a tesla?

10,000, since 1 G = 10⁻⁴ T.

What is a dyne?

The CGS unit of force: 1 g·cm/s², equal to 10⁻⁵ newton.

Why do factors of 4π appear?

CGS electromagnetic equations are written without the 4π that the SI places in its constants, so it appears in the conversion instead.

Sources: NIST Special Publication 811 (2008 ed.), Guide for the Use of the International System of Units (SI), Appendix B.9

Checked 9 Nov 2026. NIST Special Publication 811 (2008 ed.), Guide for the Use of the International System of Units (SI), Appendix B.9 “Factors for units listed by kind of quantity or field of science” — entries dyne, erg, erg per second, dyne per square centimeter, dyne centimeter, gal, poise, stokes, gauss, maxwell, oersted (7.957 747 E+01 A/m = 1000/4π), gilbert, stilb, phot and lambert.

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