About this tool
Wind Chill Calculator is a free, in-browser tool that works out how cold it feels when wind is combined with a low air temperature. Enter the temperature and wind speed, pick imperial (°F + mph) or metric (°C + km/h), and it returns the wind chill, a frostbite-risk note and a validity caveat. All maths runs locally with the values you supply — no live weather.
It uses the official 2001 North American formula. Imperial: WC = 35.74 + 0.6215·T − 35.75·V^0.16 + 0.4275·T·V^0.16, with T in °F and V in mph. Metric: WC = 13.12 + 0.6215·T − 11.37·V^0.16 + 0.3965·T·V^0.16, with T in °C and V in km/h. The V^0.16 term captures how faster wind strips heat away more quickly.
The formula is only defined for cold, windy conditions — at or below 50 °F (10 °C) with wind of at least 3 mph (4.8 km/h). Outside that range the tool still shows a number but flags it as out of the valid range. The frostbite note reflects NWS exposure times: about 30 minutes near −18 °F, 10 minutes near −32 °F, and 5 minutes near −48 °F.