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Wind Chill Factor Calculator

Calculate the wind chill factor — the NWS wind-chill temperature — from air temperature and wind speed within the equation's official applicability thresholds.

Published

Wind chill

Wind chill temperature
6 °F
Model result before display conversion
6.218885 °F
Wind speed used by NWS model
15 mph
Air temperature used by NWS model
20 °F

The NWS model always uses °F and mph; only the displayed result is converted to °F. This environmental index is not a personalized medical or frostbite-risk conclusion.

selected unit
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Results update as you type.

Worked example

windSpeed: 15 · windSpeedUnit: mph · temperature: 20 · temperatureUnit: fahrenheit

Result: 6 °F

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Wind Chill Calculator

Calculate the wind chill factor — the NWS wind-chill temperature — from air temperature and wind speed when the observations fall inside the equation’s stated scope.

Inputs and method

Enter air temperature and wind speed in any supported units. Exact conversions normalize the inputs to Fahrenheit and miles per hour. The NWS equation is:

WCT=35.74+0.6215T−35.75V0.16+0.4275TV0.16WCT = 35.74 + 0.6215T - 35.75V^{0.16} + 0.4275TV^{0.16}

Here, T is air temperature in degrees Fahrenheit and V is wind speed in miles per hour. The calculation finds a value only when converted temperature is at or below 50°F and converted wind speed is above 3 mph. Exactly 50°F is included; exactly 3 mph is not.

The formula always runs in Fahrenheit and mph. Choosing Celsius or Kelvin changes only the displayed result, not the NWS model or its scope. Intermediate values retain full precision before whole-degree display rounding.

Interpreting the estimate

Wind chill is a human-face environmental index based on adults. The NWS model assumes no effect from sunshine and uses wind speed adjusted to an average height of 5 feet from standard 33-foot anemometer readings.

Assumptions and limits

The result applies to people and animals. It does not mean an inanimate object will cool below the actual air temperature. The page does not estimate an individual’s frostbite time, risk category, or medical outcome.

The calculator rejects unsupported units, invalid numeric values, negative wind, temperatures below absolute zero, converted temperatures above 50°F, and converted wind speeds at or below 3 mph. Its numeric input limits are -100°F and 200 mph; these are interface limits, not additional NWS validity claims.

Related weather arithmetic: the heat index calculator covers the warm end of apparent temperature, the dew point calculator covers air moisture and condensation, and the wind power calculator uses wind speed as its primary input for turbine estimates.

Frequently asked questions

Do Celsius and Kelvin inputs use a different wind-chill model?

No. They are converted exactly to Fahrenheit before the applicability check and equation. The result is converted back only for display.

Why is there no value at 3 mph?

The NWS defines wind chill only for wind speeds above 3 mph. A value exactly equal to 3 mph is outside that scope.

Sources

Related glossary terms

Wind chill

Compare Wind Chill Factor Calculator with related tools

All comparisons →
Heat Index vs Wind Chill CalculatorCompare the NWS heat index and wind chill: two 'feels like' temperatures that answer opposite seasonal questions, and how to pick the right one.Wind Chill vs Dew Point CalculatorCompare wind chill and dew point: one converts temperature and wind into a cold 'feels like' number, the other converts temperature and humidity into the saturation point where surfaces frost or condense.Wind Chill vs HumidexCompare the two apparent-temperature indices: the NWS wind-chill temperature for cold, windy conditions versus the Environment Canada humidex for hot, humid conditions.

Frequently asked questions

What inputs does the wind chill formula use?
The NWS equation uses air temperature in degrees Fahrenheit and wind speed in miles per hour. Inputs in other units are converted exactly to Fahrenheit and miles per hour before the equation runs, and choosing Celsius or Kelvin changes only the displayed result.
When does the calculator show a wind chill value?
It finds a value only when the converted temperature is at or below 50 degrees Fahrenheit and the converted wind speed is above 3 mph. Exactly 50 degrees is included, but exactly 3 mph is not, because the NWS defines wind chill only for wind speeds above 3 mph.
Why is wind chill different from the actual air temperature?
Wind chill is a human-face environmental index based on adults. The NWS model assumes no effect from sunshine and uses wind speed adjusted to an average height of 5 feet from standard 33-foot anemometer readings. The result does not mean an inanimate object will cool below the actual air temperature.

Sources

  • Wind Chill Chart

    primary · Aug 10, 2026

    Supports: The NWS wind-chill equation, its applicability thresholds (temperature at or below 50°F and wind above 3 mph), and the model's assumptions (5-foot height adjustment, no sunshine effect).

    — National Weather Service

  • SI Units: Temperature

    primary · Aug 10, 2026

    Supports: Exact temperature conversions and absolute zero used for Celsius and Kelvin input normalization and physical-temperature validation.

    — National Institute of Standards and Technology (NIST)

  • SI Units: Length

    primary · Aug 10, 2026

    Supports: Exact mile and time relationships used for converting km/h and m/s wind speeds to the mph the NWS model requires.

    — National Institute of Standards and Technology (NIST)

  • NIST Handbook 44 (2026), Appendix C

    primary · Aug 10, 2026

    Supports: International nautical mile and knot definitions used for the knot wind-speed conversion.

    — National Institute of Standards and Technology (NIST)

  • NIST Guide to the SI, Chapter 8

    primary · Aug 18, 2026

    Supports: exact mile and time relationships used for wind-speed conversion

    — National metrology institute

Related calculators

Heat Index CalculatorCalculate the NWS heat index — the feels like temperature — from air temperature and relative humidity or dew point, including the official branch decision and humidity adjustments.Humidex CalculatorCalculate the humidex from air temperature and dew point with the Environment Canada formula, and read the comfort category from little discomfort to dangerous.Dew Point CalculatorPerform a dew point calculation from air temperature and relative humidity, with condensation, comfort, weather, and building-moisture guidance.Relative Humidity Calculator: From Temperature & Dew PointCalculate relative humidity from air temperature and dew point with the Magnus-Tetens formula, plus comfort ranges, condensation, and mold-risk guidance.Plant Growth CalculatorCalculate daily and cumulative growing degree days from temperatures and a base you enter.Kelvin to Fahrenheit ConverterConvert Kelvin to Fahrenheit and Fahrenheit to Kelvin for physics and engineering with exact offset formulas, examples, and absolute-zero checks.

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