How to use the wind chill calculator
Enter the air temperature in degrees Fahrenheit and the wind speed in miles per hour, and the page applies the wind chill index used by the National Weather Service. The values that actually went into the equation are printed with the result, along with the equation itself, so you can see exactly what was calculated. A Celsius conversion of the answer is shown as well.
The equation is 35.74 + 0.6215×T − 35.75×V^0.16 + 0.4275×T×V^0.16, with T in degrees Fahrenheit and V in miles per hour. It is valid only at 50 °F or below and above 3 mph, and the page refuses to calculate outside that range. It is the index the National Weather Service and Environment Canada adopted jointly in 2001; Environment Canada publishes the same index in metric form (13.12 + 0.6215×T − 11.37×V^0.16 + 0.3965×T×V^0.16, °C and km/h). Your entries go into the equation unrounded, and the result is rounded only once, for display. The current index was calibrated with human trials carried out in Toronto, Canada in 2001; the earlier index is described as having underestimated the time to freezing. Current as of October 2026.
The published chart shades the time for exposed skin to become frostbitten into three bands of 30, 10 and 5 minutes, but the wind chill values that separate those bands are not confirmed in an authoritative source. This page therefore records only that three bands exist plus one confirmed worked example, and calculates no exposure time. It also does not stage hypothermia by core body temperature. This is a weather conversion tool and not a medical assessment of your health. If shivering stops or speech becomes slurred or awareness fades, seek medical care without delay.
Frequently asked questions
The wind chill index was built to apply only at air temperatures of 50 °F or below and wind speeds above 3 mph. Outside that range the formula returns a number that does not match reality, so the page shows a notice instead.
No. The published chart is known to shade three exposure bands of 30, 10 and 5 minutes, but the wind chill values that separate those bands are not confirmed in an authoritative source, so no exposure time is calculated.
No. This page applies only the wind chill equation, which combines air temperature in degrees Fahrenheit with wind speed in miles per hour. It does not stage hypothermia by core body temperature and it does not estimate how long you can stay outside.