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.
Open calculatorLast 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.
Worked example
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.
Wind chill (°F) by air temperature and wind speed
| Air temperature | 5 mph | 10 mph | 15 mph | 20 mph | 30 mph |
|---|---|---|---|---|---|
| 40 °F | 37 | 34 | 32 | 31 | 29 |
| 30 °F | 25 | 21 | 19 | 17 | 15 |
| 20 °F | 13 | 9 | 6 | 4 | 1 |
| 10 °F | 1 | -4 | -7 | -9 | -12 |
| 0 °F | -11 | -16 | -19 | -22 | -26 |
| -10 °F | -22 | -28 | -32 | -35 | -39 |
The index applies to air at or below about 50 °F and winds above about 3 mph.
Worked scenario: 20 °F with a 15 mph wind
The wind chill is 6.2 °F (-14.3 °C). Exposed skin loses heat as though the air were that cold.
What wind chill does not mean
- It describes heat loss from exposed skin. Wind does not cool a pipe, a car or a plant below the air temperature itself.
- It speeds up how quickly an object reaches the air temperature, so a pipe in a draught freezes sooner than one in still air, but not at a higher temperature.
- It assumes a person walking, in shade, with exposed skin. Clothing and shelter change the real exposure.
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.