Wind Chill Calculator
Enter temperature and wind speed to get the wind chill and how quickly frostbite can develop — the official US weather service formula.
Last updated: 2026-09-15
How the calculation works
- Wind strips the warm boundary layer of air next to skin, accelerating heat loss — the formula quantifies that as an equivalent still-air temperature.
- The 0.16 exponent comes from wind-tunnel testing on human subjects in the 2001 revision of the index.
- Frostbite bands estimate time to freezing of exposed tissue.
Formula
WC = 35.74 + 0.6215T − 35.75·V^0.16 + 0.4275·T·V^0.16
| Symbol | Meaning | Unit |
|---|---|---|
WC | Wind chill temperature | °F |
T | Air temperature | °F |
V | Wind speed | mph |
Worked example
10 °F with 20 mph wind: wind chill ≈ −9 °F — frostbite possible on exposed skin in about 30 minutes. The same 10 °F with 5 mph wind feels like 1 °F: wind speed dominates the risk.
Interpreting the result
Wind chill applies to living things only — your car engine, water pipes and heat pump cool to actual air temperature regardless of wind. The practical uses: dressing for wind chill, protecting workers outdoors, and estimating how fast exposed skin freezes. It does not change refrigeration or freezing physics.
Assumptions
- Standard human model: walking pace, winter clothing on torso, exposed face.
- Valid ≤ 50 °F and ≥ 3 mph.
Limitations
- Does not apply to objects or to water freezing.
- Sunlight can raise apparent temperature several degrees.
Frequently asked questions
At what wind chill does skin freeze?
Around −18 °F wind chill, frostbite takes about 30 minutes on exposed skin; below −35 °F it can happen in under 10 minutes.
Does wind chill affect pipes freezing?
No. Water freezes at the actual air temperature; wind accelerates heat loss from the pipe but the threshold is 32 °F air, not wind chill.