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Wind Chill Calculator

Find how cold it feels on bare skin from the air temperature and wind speed, using the 2001 North American wind chill index.

Level: Grades 9–10

Printable worksheet

Wind Chill Calculator

Inputs
Units

Result

Wind chill

6.2 °F

At 20 °F with 15 mph wind, it feels like 6.2 °F. Low risk, rising with long exposure; cover up.

In Celsius
-14.3 °C
Wind chill effect
-13.8 °FHow much colder than the air it feels on exposed skin.
General frostbite guidance
Low risk, rising with long exposure; cover upA rough guide for healthy adults with exposed skin; not medical advice.

See the step-by-step solution ↓

Step-by-step solution

  1. Raise the wind speed (mph) to the power 0.16. This makes the first few mph of wind count most

    150.16=1.54232

  2. Put the temperature (T, in °F) and that wind factor into the 2001 wind chill formula

    35.74+0.6215×20−35.75×1.54232+0.4275×20×1.54232=6.218885

  3. Change to Celsius for comparison: subtract 32, then multiply by 5 ÷ 9

    6.218885−32×0.555556=−14.322842

Test yourself

20 quick questions built from this calculator's formula: work out results, predict what happens when an input changes, and work backward from an answer. Every answer comes with the working.

What this calculator does

Find out how cold it really feels on your bare skin once the wind is blowing. Wind makes cold air feel colder. It strips away the thin layer of warmer air that sits against your skin. The wind chill index puts a number on that effect. It's the calm-air temperature that would cool bare skin as fast as today's temperature and wind together. This calculator uses the index the US and Canadian weather services adopted together in 2001. It works in Fahrenheit and miles per hour, or Celsius and kilometers per hour.

The index only makes sense when it's cold and the air is moving. So the calculator checks the valid range before using it. It also gives a broad, general idea of how quickly bare skin could freeze. That's the same kind of banded guidance weather services publish with cold-weather warnings.

Where it's used

Why this math matters outside the classroom:

  • School recess. Schools use wind chill forecasts to decide whether children have recess indoors.
  • Worked example. At 0 °F with a 15 mph wind, the 2001 wind chill index gives about −19 °F.
  • Outdoor crews. Construction and utility crews plan shorter stretches outside when the wind chill drops sharply.
  • Winter hiking. Winter hikers pack extra layers for exposed ridges, where stronger wind lowers the wind chill.

How to use it

  1. Choose °F and mph or °C and km/h.
  2. Enter the air temperature and the sustained (steady) wind speed. A forecast or nearby weather station is the best source.
  3. Read the wind chill, its value in the other unit, and how many degrees colder than the air it feels.
  4. Use the frostbite guidance as a rough reminder to cover bare skin, not as a precise time limit.

What the inputs mean

Air temperature
The measured air temperature. The wind chill index applies at 50 °F or below.
Wind speed
Sustained wind speed as weather services report it. They measure it about 10 m (33 ft) above the ground. Below 3 mph, the index isn't used.

Formula and method

WC(°F) = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16   (T in °F, V in mph)
WC(°C) = 13.12 + 0.6215T − 11.37V^0.16 + 0.3965TV^0.16   (T in °C, V in km/h)
valid for T ≤ 50 °F (10 °C) and V ≥ 3 mph (about 4.8 km/h)

WC is the wind chill, T is the air temperature and V is the wind speed. V^0.16 means V raised to the power 0.16. Both lines are the same index, written for different units. Any tiny differences between them come only from rounding the published numbers. Because of that small power, the first few miles per hour of wind make the biggest difference. Each extra mile per hour adds less.

The index was built from a model of how fast a person's face loses heat while walking. It adjusts the wind from the 10 m height where it's measured down to face level. That's why it uses the reported station wind, not a reading taken at ground level.

Outside its valid range, the calculator doesn't stretch the formula. Above 50 °F, or in nearly calm air, it shows the air temperature itself and says why.

Worked example

The air temperature is 20 °F and the wind is blowing at 15 mph.

  1. Wind factor: 15^0.16 = 1.5423.
  2. 35.74 + 0.6215 × 20 = 48.17.
  3. Subtract 35.75 × 1.5423 = 55.138 and add 0.4275 × 20 × 1.5423 = 13.187.
  4. Wind chill: 48.17 − 55.138 + 13.187 = 6.2 °F, which is about −14.3 °C.

Result: It feels like 6.2 °F, about 13.8 degrees colder than the air. On the general guidance bands, the frostbite risk is low, but it rises with long exposure.

Understanding the result

A wind chill isn't the temperature of objects. A car or a water pipe won't cool below the air temperature, however hard the wind blows. Wind chill describes how fast bare skin loses heat.

In the broad guidance shown here, about −28 °C (−18 °F) is the key point. At wind chills that low or lower, weather services warn that bare skin can freeze within half an hour. That time shrinks quickly as the wind chill falls.

Treat the frostbite bands as approximate. Wet skin, poor circulation and long exposure all raise the risk. So does being a child or an older adult.

Assumptions and limitations

  • Wind speed is the sustained wind at the standard 10 m measuring height.
  • The index assumes a person walking at about 5 km/h in the shade, with dry, bare skin on the face.
  • It assumes night-time or cloudy conditions. Strong sunshine can make it feel noticeably warmer.
  • It isn't defined above 50 °F (10 °C) or below 3 mph (about 4.8 km/h). The air temperature is shown instead.
  • The frostbite bands are general guidance. They don't account for clothing, health or activity, and they aren't medical advice.
  • It ignores humidity, sunshine and the extra cooling of wet skin or clothing.

Frequently asked questions

Why doesn't wind chill apply above 50 °F?

The index was designed for cold conditions, where heat loss from skin is a hazard. In mild weather, a breeze mostly feels pleasant. Other things, such as humidity and sunshine, matter more. So the formula isn't used there.

Can wind chill freeze water above 32 °F?

No. Wind speeds up cooling, but it can't cool an object below the air temperature. Water in 35 °F air won't freeze, whatever the wind chill reads. Wet skin does feel the cold much more, though.

Why does the result differ slightly between °F and °C?

The two published versions use rounded numbers. So converting the inputs and running the other formula can differ by a few tenths of a degree. Forecasts round wind chill to whole degrees, so the difference doesn't matter in practice.

Is this the same as the 'feels like' temperature in weather apps?

In cold weather, many apps show the wind chill as 'feels like'. In hot weather, they switch to a heat index that uses humidity instead. Some apps use their own blends, so numbers can differ slightly.

How this calculator is checked

Method: Wind chill temperature index adopted by the US National Weather Service and Environment Canada in 2001 (°F/mph and °C/km/h forms). The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

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