How to use the Wind Chill Calculator
- Enter the air temperature in Fahrenheit.
- Enter the wind speed in miles per hour, as measured at standard height.
- Read the wind chill in Fahrenheit and Celsius.
- Note how much colder it feels than the thermometer reading.
- Check the frostbite risk before planning exposure.
How the calculation works
Wind chill quantifies how much faster moving air strips heat from exposed skin. Still air holds a thin insulating boundary layer against the skin; wind removes it continuously, so heat is lost by forced convection rather than the slower natural convection. The result is a lower effective skin temperature even though the air temperature has not changed at all.
The current formula dates from 2001, replacing a 1945 version based on the freezing rate of water in a plastic cylinder. The modern model uses a human face at 5 feet above ground, assumes calm skin temperature of 91.4°F, and incorporates measured heat-transfer rates from human trials. It applies at or below 50°F with winds above 3 mph, and reports the plain temperature outside those bounds.
Frostbite risk is the practical output. At a wind chill of −18°F exposed skin can freeze within about 30 minutes; at −30°F that drops to roughly 10 minutes, and near −50°F to under 5. Crucially, wind chill affects exposed skin and living tissue only — a parked car or a water pipe cools to the actual air temperature, never below it, however hard the wind blows.
WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275T·V^0.16, with T in °F and V in mph, valid for T ≤ 50°F and V > 3 mphSource: US National Weather Service / Environment Canada Wind Chill Temperature Index (2001).
Worked example
A site crew works at 5°F with a 25 mph wind.
- V^0.16 = 25^0.16 = 1.6885.
- 35.74 + 0.6215 × 5 = 38.85.
- −35.75 × 1.6885 = −60.36; +0.4275 × 5 × 1.6885 = +3.61.
- Sum: 38.85 − 60.36 + 3.61 = −17.9°F.
About −18°F wind chill, 23 degrees below the thermometer, at which exposed skin can freeze in roughly 30 minutes.
Frequently asked questions
Does wind chill affect objects?+
No. Wind makes objects reach air temperature faster, but never colder than it. Only living tissue generating its own heat experiences wind chill.
Why does the formula stop at 3 mph?+
Below that, air movement is negligible and the model returns values above the actual temperature, which is meaningless. The plain temperature is reported instead.
Can wind chill be warmer than the air temperature?+
Not within the valid range. Above 50°F the concept does not apply, and heat index becomes the relevant measure.
How should I dress for it?+
Layer for the wind chill figure, not the thermometer, and cover extremities — fingers, ears and nose freeze first because they have the highest surface-to-volume ratio.
Last reviewed August 31, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.