Wind Chill Calculator
Enter a measured temperature and wind speed to see the NWS estimate only where its formula applies, with the rounding and model limits beside the answer.
Wind chill estimate
- Entered air temperature
- Entered wind speed
- Converted for NWS formula
Converted numbers below are shown with up to 12 significant digits; the calculation keeps full precision.
Show formula substitution and rounding
Fahrenheit and Celsius are calculated from the unrounded result, then each displayed to one decimal. The whole-degree values are separately rounded for comparison. True halfway values round away from zero.
Calculation, copying and text export use this browser. This page does not look up your location or fetch weather observations. Copies and downloaded files go only where you choose.
Read the estimate in its valid range
The NWS wind-chill temperature estimates the effect of wind and cold on exposed skin. It is defined for measured air temperature at or below 50°F and wind speed above 3 mph. The page keeps the raw normalized numbers for this test, so a rounded unit display cannot turn an out-of-domain input into a result. Above 50°F, at 3 mph or less, or both, it shows the specific reason and no wind-chill estimate. “Not defined” does not mean safe; cold air can still be hazardous without wind.
Formula, units and rounding
The NWS formula is 35.74 + 0.6215T − 35.75(V^0.16) + 0.4275T(V^0.16), with T in °F and V in mph. A Celsius input is converted using °F = °C × 9/5 + 32; km/h is divided by 1.609344 to obtain mph. For 0°F and 10 mph, the unrounded formula result is approximately −15.9345°F. That becomes −15.9°F at one decimal and −16°F at a whole degree. Celsius is calculated from the unrounded Fahrenheit result, then rounded separately. The result's formula panel shows the numbers substituted into the formula.
Safety and interpretation limits
The NWS index models an adult face exposed to wind and assumes no sun. Bright sun, clothing, individual health and local conditions can change a person's experience. Children, older adults and medically vulnerable people may need extra caution. Wind chill does not mean a pipe or car can cool below the actual measured air temperature through wind alone. This calculator does not know local weather, issue a warning, diagnose an injury or promise a safe exposure duration. For current conditions or alerts, consult the National Weather Service.
Local calculation and next step
Enter your own measurements; there is no location lookup, weather API or live observation behind the calculation. Once this page's static assets are loaded, a new calculation and text export can run without a network connection. If you need to convert a different temperature scale first, use the related temperature converter below. The official NWS sources above give the model and current safety context.
Frequently asked questions
What formula does this wind chill calculator use?
It uses the U.S. National Weather Service formula in Fahrenheit and miles per hour: 35.74 + 0.6215T − 35.75(V^0.16) + 0.4275T(V^0.16). T is measured air temperature and V is measured wind speed. The formula estimates exposed-skin heat loss, not actual air temperature.
When is the NWS wind-chill formula defined?
Only at air temperatures of 50°F or lower and wind speeds above 3 mph. At exactly 50°F and 3 mph it is not defined because the wind-speed boundary is strict. This page shows a reason instead of inventing a wind-chill number outside the range. Cold, calm conditions can still be dangerous.
Can I enter Celsius and kilometers per hour?
Yes. Celsius is converted to Fahrenheit and km/h to mph before the NWS domain check and formula. Unit changes preserve the underlying unrounded measurement until you edit the displayed one-decimal value. The Fahrenheit and Celsius answers are each rounded from the unrounded result.
Why might another wind-chill calculator show a different number?
Display precision can differ even when the same NWS formula is used. For 0°F and 10 mph, the unrounded estimate is about −15.9345°F. One decimal gives −15.9°F; a whole degree gives −16°F. This page labels both so they are not mistaken for different physical models.
Can wind chill make a pipe or car colder than the air?
No. Wind can bring an inanimate object toward the measured air temperature faster, but wind chill does not lower it below that air temperature by itself. The NWS index concerns heat loss from exposed skin, not a new thermometer reading for objects.
Does this result tell me how long I can stay outside or when a warning applies?
No. The NWS index is based on an adult-face model and assumes no impact from the sun. Children, older adults and people with compromised health may need extra caution. Local warning criteria vary. This calculator gives no personalized frostbite clock, diagnosis or official advisory. Check current local NWS conditions for decisions about exposure.