Wind Chill Calculator – Free Calculator

Understanding the wind chill calculator — concept and principle

Wind chill expresses how cold it feels on exposed skin when wind is added to low temperature. Wind strips away the thin layer of warm air next to your skin, so you lose heat faster than in calm air at the same temperature. The calculator uses the formula adopted by Environment Canada and the US National Weather Service in 2001.

A 20 km/h wind turns −5 °C into a felt −11.6 °C.

How it is calculated

WCT = 13.12 + 0.6215 × T − 11.37 × V^0.16 + 0.3965 × T × V^0.16

T is the air temperature in °C.
V is the wind speed in km/h measured at the standard height of 10 m.

The formula applies only when T ≤ 10 °C and V > 4.8 km/h. Outside that range the calculator simply returns the air temperature.

The principle

The 2001 index was developed by R. Osczevski and M. Bluestein from a heat-transfer model of a human face walking into the wind at about 5 km/h, checked with volunteers in a wind tunnel. It assumes the skin is dry, there is no sunshine and the face is the most exposed part of the body. The result is the air temperature that, in a light breeze, would cool the face at the same rate. The term V^0.16 reflects how convective heat loss grows with wind speed but at a slowing rate.

Worked example

Inputs: T = −5 °C, V = 20 km/h. Both conditions are met.
V^0.16 = 20^0.16 = 1.61497.
0.6215 × (−5) = −3.1075.
11.37 × 1.61497 = 18.3622.
0.3965 × (−5) × 1.61497 = −3.2017.
WCT = 13.12 − 3.1075 − 18.3622 − 3.2017 = −11.55140381 °C.

Each point is the calculator re-run with only “Air temperature (°C)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Air temperature (°C)	Wind chill (°C)
-1.25	-6.819518413
-2.5	-8.396813546
-3.75	-9.974108679
-5	-11.55140381
-6.25	-13.12869895
-7.5	-14.70599408
-10	-17.86058434

How to read the result

Where does your result fall?

Environment Canada groups wind chill into risk levels: 0 to −9 low risk; −10 to −27 moderate (uncomfortable, risk of hypothermia with long exposure without protection); −28 to −39 high (exposed skin can freeze in 10–30 minutes); −40 to −47 very high (5–10 minutes); −48 to −54 severe (2–5 minutes); −55 and below extreme (under 2 minutes). The example falls in the moderate band: dress in layers and cover the face and hands for long walks.

Common mistakes

Using wind speed in m/s; multiply by 3.6 to get km/h.
Thinking wind chill lowers the temperature of objects; a car or water pipe cannot cool below the actual air temperature.
Using gusts or wind at ground level instead of the standard 10 m wind from the forecast.

Keep in mind: Wind chill is a guide for exposed skin and does not diagnose frostbite or hypothermia. Wet clothing, exhaustion, alcohol, age and poor circulation raise the risk well beyond what the number suggests.

Frequently asked questions

Does the Korea Meteorological Administration use the same formula?

Its winter feels-like temperature is based on this same 2001 equation using temperature and wind speed.

Why does the formula stop at 10 °C?

Above that, wind is often pleasant and humidity and sunshine dominate comfort, so other indices are used.

How is wind chill different from the old index?

The pre-2001 Siple and Passel index exaggerated cooling at high winds; the current formula is based on modern heat-transfer research and human trials.

Sources: R. Osczevski and M. Bluestein, The New Wind Chill Equivalent Temperature Chart, Bulletin of the American Meteorological Society 86(10), 1453–1458 (2005) · Environment and Climate Change Canada, Wind chill index · NOAA National Weather Service, Wind Chill Chart

Checked 8 Nov 2026. Standard textbook formulas in SI units, computed in your browser. For learning and estimates — real designs must follow your local codes and be checked by a qualified engineer.

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