How wind chill calculator works
Wind chill answers one question: how fast does bare skin lose heat? Moving air strips away the thin warm layer your body heats around itself, so the same air temperature feels colder as wind rises. The NWS wind chill formula WCI = 35.74 + 0.6215·T − 35.75·V^0.16 + 0.4275·T·V^0.16 (T in °F, V in mph) models that combined cooling from clinical cold-exposure trials.
Enter an air temperature (°F or °C) and a wind speed (mph, km/h, m/s or knots). The tool converts to the formula's native units, computes the wind chill in °F and °C, and places the result on the NWS Wind Chill Chart's frostbite-time bands: about 30 minutes of exposure at −18°F or colder, 10 minutes at −32°F or colder, and 5 minutes at −48°F or colder.
The formula is only defined for air temperatures at or below 50°F and winds of at least 3 mph — outside that range the NWS does not define wind chill, and the tool says so rather than inventing a number. Wind chill affects living skin only: water pipes and car engines cool to the actual air temperature, no colder.