US Wind Chill Calculator
Estimate wind chill with the US formula using air temperature and wind speed in mph.
Formula and sources updated · Data sources · 1View algorithm, constants and default inputs (JSON)
About this calculator
This is the US wind-chill temperature formula, not a thermometer reading or personal frostbite-time estimate. Wind speed must be in mph, even when air temperature is entered in Celsius. The formula is defined only at or below 50°F and above 3 mph; outside that range the calculator reports an error instead of presenting air temperature as wind chill.
Worked example
calculated with the default values below
Air temperature 25 °F · Wind speed 15 mph · Temperature unit Fahrenheit Wind chill 12.6 °F · Wind chill -10.8 °C
Method and assumptions
Formula basis and scope
Uses the NWS Fahrenheit/mph wind-chill relationship with coefficients 35.74, 0.6215, −35.75 and 0.4275, and wind speed raised to 0.16.
Inputs above 50°F or at wind speeds of 3 mph or less are rejected. Estimates perceived cold on exposed skin, not an object temperature or an individualized injury timer.
Data sources
Disclaimer
These calculators give general estimates. Sizing, pricing, availability and standards vary by brand, retailer and country, so treat the output as a starting point and confirm it against the seller's or authority's own figures.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
W = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16
- T
- Air temperature (°F)
- V
- Wind speed (mph)
- W
- Wind chill (°F)
US equation with T in °F and V in mph; Celsius input is converted. Defined only for T≤50°F and V>3mph. This result is not a personal frostbite-time estimate. [NWS formula and limits](https://www.weather.gov/safety/cold-wind-chill-chart).
Frequently asked questions
When is the US wind-chill formula defined?
The NWS formula is defined for air temperatures at or below 50°F and wind speeds above 3 mph. This calculator uses mph for wind even when temperature is entered in Celsius. It reports an error outside the formula range, and it does not predict frostbite time or issue a local warning. [National Weather Service](https://www.weather.gov/safety/cold-wind-chill-chart).