Wind Chill Calculator

1. Enter the air temperature, in Fahrenheit or Celsius.
2. Enter the wind speed, in mph or km/h.
3. Read the wind chill, the temperature it actually feels like.
4. See how many degrees colder it feels, and the approximate frostbite risk.

Here is what each result means:

Wind chill is the temperature your exposed skin actually feels, not what a thermometer reads. Moving air pulls heat away from your body faster than still air does, so a windy 20 degree F day feels much colder than a calm one at the same temperature.

The wind chill value is always calculated for a specific combination of air temperature and wind speed. It only applies to exposed skin, not to water pipes, car radiators, or other objects, which cool at different rates than the human body.

It applies the official North American wind chill formula, developed from skin heat-loss experiments.

1. Convert temperature to Fahrenheit and wind speed to mph if entered in other units.
2. Raise the wind speed to the power of 0.16.
3. Apply the formula to combine temperature and wind speed into a single wind chill value.
4. Convert the result back to your chosen display unit.

This formula, adopted by the US National Weather Service and Environment Canada in 2001, is only valid at or below 50 degrees F with a wind speed of at least 3 mph. Outside that range, wind has little meaningful chilling effect on exposed skin.

Find the wind chill at 20 degrees F with a 25 mph wind.

Calculation: WC = 35.74 + 0.6215(20) - 35.75(25^0.16) + 0.4275(20)(25^0.16), which works out to about 3 degrees F. Even though the thermometer reads 20 degrees, exposed skin loses heat as fast as it would at 3 degrees F in calm air.

Colder wind chill values shorten the time exposed skin takes to develop frostbite. The bands below approximate the official NWS wind chill chart based on the wind chill value alone; the full NWS chart considers exact temperature and wind speed combinations, so treat this as a general guide, not a precise timer.

Wind Speed

Faster wind strips heat away more quickly, but the effect grows more slowly once wind speed is already high. Going from calm to a light breeze drops the felt temperature sharply; going from a strong wind to an even stronger one adds less.

Air Temperature

Wind chill only matters when the air is already cold. Above about 50 degrees F, wind has little meaningful cooling effect on skin.

Sun, Moisture, and Clothing

Direct sunlight, wet skin or clothing, and how well you are dressed all change how cold you actually feel, but none of these are part of the standard wind chill formula, which only uses temperature and wind speed.

Planning Outdoor Activities

Check the wind chill before a hike, a run, or working outside in cold weather to judge how much exposed skin is at risk.

Deciding What to Wear

A low wind chill number is a clear signal to cover exposed skin, not just to add a layer under a coat.

Understanding a Weather Forecast

Forecasts often report wind chill alongside air temperature. Knowing how the two differ helps you read a forecast correctly.

1. Applying Wind Chill to Objects

Wind chill only describes heat loss from exposed skin. A car engine or a water pipe cools at a different rate and does not follow this formula.

2. Using It Above 50 Degrees F

The formula is not calibrated for mild temperatures. Wind has little meaningful chilling effect once the air itself is not cold.

3. Ignoring Very Light Wind

Below about 3 mph, the formula becomes unstable and wind chill is treated as equal to the air temperature, since there is not enough airflow for the formula to apply.

4. Confusing Wind Chill With Heat Index

Wind chill measures how cold it feels in cold, windy weather. Heat index measures how hot it feels in hot, humid weather. They use different formulas and apply to opposite conditions.

The formula is exact within its valid range; only the displayed decimals are rounded.

Wind chill uses the 2001 North American formula, which combines air temperature and wind speed raised to the power of 0.16. At 20 degrees F with a 25 mph wind, the wind chill works out to about 3 degrees F.

Air temperature is what a thermometer reads. Wind chill is how cold exposed skin actually feels once wind is factored in, since moving air pulls heat away from skin faster than still air.

Below about 3 mph, the wind chill formula becomes unreliable, so wind chill is treated as equal to the actual air temperature at very low wind speeds.

The official formula is only valid at or below 50 degrees F. Above that, wind has little meaningful cooling effect on exposed skin, so wind chill is not calculated.

No. Wind chill only describes heat loss from exposed human skin. Objects like water pipes or engines cool according to the actual air temperature, not the wind chill value.

It is an approximate band based on the wind chill value alone. The official NWS wind chill chart considers the exact combination of temperature and wind speed, so treat this as a general guide and check official warnings in genuinely dangerous cold.

No. Wind chill measures how cold it feels in cold, windy weather. Heat index measures how hot it feels in hot, humid weather. They use different formulas for opposite conditions.

No. The calculation runs in your browser and nothing you enter is stored or sent anywhere, unless you choose Save, which keeps the result only on this device.

• Wind Chill Temperature Index (National Weather Service).
• Wind Chill Equation (National Weather Service).