This wind chill calculator estimates how cold it feels when wind moves across exposed skin. Enter air temperature in Fahrenheit and wind speed in mph. The default 20°F with 15 mph wind returns about 6.22°F wind chill.
Check conditions before winter outdoor plans, then dress for the feels-like number rather than the calm air reading alone. For general unit conversion before you enter values, use the unit converter.
How the formula works
For cold, windy conditions the tool applies 35.74 + 0.6215T – 35.75×v^0.16 + 0.4275T×v^0.16. If T is above 50°F or wind is under 3 mph, it returns T unchanged.
Worked example
T = 20, v = 15. Both sit inside the formula window, so the wind chill evaluates to about 6.22.
| Input | Value |
|---|---|
| Air temperature | 20°F |
| Wind speed | 15 mph |
| Wind chill | about 6.22°F |
How to use the fields
- Air temperature is the thermometer reading in °F.
- Wind speed is sustained wind in mph.
Validity window
Wind chill charts are built for cold air and meaningful wind. Warm breezes or nearly calm air do not use the same relation, which is why the calculator falls back to air temperature outside that window.
Common mistakes
- Entering Celsius in the Fahrenheit field
- Using km/h without converting to mph
- Treating wind chill as a measured air temperature
- Ignoring calm conditions where wind chill is not applied
Outdoor planning
A calm 20°F day and a windy 20°F day do not feel the same. Use the default style inputs to compare clothing needs when wind rises while the thermometer stays fixed.
Classroom practice
Hold temperature at 20°F and raise wind from 5 to 15 mph. Students should see wind chill fall. Then set wind to 2 mph and show the fallback to air temperature.
Convert a Celsius weather app reading to Fahrenheit before using the tool so unit errors do not hide inside the formula.
Safety note
Wind chill is a planning aid, not a medical device. Frostbite risk also depends on exposure time, wet clothing, and individual factors the calculator does not model.
Clothing and exposure
Wind chill assumes exposed skin. Covered skin changes heat loss. Use the number to plan layers, not to claim a precise body temperature.
Wet clothing worsens heat loss beyond what wind chill alone captures. Dry layers matter as much as the calculated feels like value.
Gusts versus sustained wind
Forecasts may list gusts higher than sustained wind. This calculator expects the wind speed field you choose to interpret. For conservative planning, some people enter a higher wind value knowingly.
Say which wind definition you used when sharing results with a group.
Unit conversion workflow
If your weather app shows Celsius and km/h, convert before entry. Mixing unit systems is the most common source of nonsense wind chill numbers.
After conversion, sanity check: colder air and stronger wind should not produce a warmer feels like value inside the valid window.
Indoor versus outdoor sensors
Phone weather apps estimate conditions for a region. A backyard anemometer can disagree. Prefer the wind and temperature pair measured at your location when safety decisions are local.
Vehicle speed adds relative wind when you ride a bike or motorcycle. That relative wind is not what a stationary weather station reports.
Say whether your wind input is station wind or travel relative wind when you document a ride plan.
Communication clarity
When you text a group about conditions, send both air temperature and wind chill. Sending only one number causes mixed preparation.
Include units every time. A bare 6 could mean 6°F wind chill or 6 mph wind depending on who reads the thread.
Limitations
Fahrenheit and mph only. No humidity term, no solar load, and no altitude adjustment.