Wind Chill Calculator
Estimate wind chill — how cold exposed skin feels when wind speeds up heat loss. Uses the modern North American (NWS/MSC) equation.
Calculate
Calculate
Measurements convert when you switch units
Result
The formula
Wind chill models convective heat loss from skin at cold temperatures. The metric form uses air temperature in °C and wind speed in km/h. Imperial mode converts to the Fahrenheit/mph twin equation used by the US National Weather Service.
Worked example
- Air temperature −5 °C
- Wind speed 30 km/h
- Wind chill ≈ −13 °C
Result: Feels like ≈ −13 °C
How wind chill is defined
Wind chill is a “feels like” index for cold, windy conditions — not a thermometer reading of objects outdoors.
Valid range
The standard chart is intended for cold air (roughly ≤10 °C / 50 °F) with meaningful wind. Outside that range we show air temperature instead of inventing a misleading chill value.
What it measures
Moving air strips the thin warm boundary layer next to skin, accelerating heat loss. The index estimates that sensation for exposed skin under standardized assumptions.
Frostbite and safety
Frostbite risk depends on wind chill, exposure time, wetness, and clothing. Use official NWS frostbite timing charts for planning — this page is an index calculator, not a medical device.
Objects vs people
A parked car’s thermometer still reads air temperature. Wind chill describes human heat loss, not the temperature of inanimate objects.
Interesting facts
Only for cold conditions
Wind chill is defined for cold air with meaningful wind — not for warm breezy days (use heat index there).
Not the same as frostbite time
The index is a “feels like” value. Frostbite clocks also need exposure duration and clothing.
Why wind bites
Moving air removes the warm layer next to skin, speeding heat loss — the physics behind the formula.
Updated in the early 2000s
Modern NWS/MSC equations replaced older wind-chill charts that overstated how cold it felt.
Calm wind caveat
At very low wind speeds the index is not applied; calm cold air is reported as the air temperature.
Frequently asked questions
Enter air temperature and wind speed. We apply the NWS/MSC formula in metric or imperial units via the toggle.
Use the unit toggle. Metric uses °C and km/h; imperial uses °F and mph.
Outside the valid cold/wind range, wind chill is not defined, so we show the air temperature.
Wind increases heat loss from warm objects, but the equilibrium temperature of objects still approaches air temperature — the index is calibrated for skin, not engine blocks.
US NWS frostbite-time charts show exposed skin can develop frostbite in as little as 30 minutes around −28 °C (−18 °F) wind chill, and faster at more extreme values. Always check official NWS charts for exposure-time planning.
The formula is only valid for cold air with meaningful wind, roughly ≤10 °C (50 °F). Outside that range the calculator shows plain air temperature instead of an undefined or misleading chill value.
Most English-speaking countries, including the US and Canada, use the same modern NWS/MSC equation adopted in the early 2000s. Some countries use related but distinct indices, so exact numbers can vary slightly by source.
References
- Wind chill chart and equation Official US wind-chill formula and frostbite guidance.
- Wind chill program Canadian partner standard for the same modern index.