Wind Chill Calculator
Enter the air temperature and wind speed to find how cold it feels on bare skin, and roughly how long until frostbite could start. The formula is only valid for air at or below 50 F (10 C) and wind of at least 3 mph (4.8 km/h).
Updated
Report a problem
Formula
Imperial (NWS 2001), T in F and V in mph:
WC = 35.74 + 0.6215T − 35.75 V^0.16 + 0.4275 T V^0.16
Metric (Environment Canada), T in C and V in km/h:
WC = 13.12 + 0.6215T − 11.37 V^0.16 + 0.3965 T V^0.16
Valid for air at or below 50 F (10 C) and wind of at least 3 mph (4.8 km/h).
Frostbite bands (exposed skin, wind chill in C)
| Wind chill | Note |
|---|---|
| above −10 | Frostbite unlikely |
| −10 to −27 | Low risk |
| −28 to −39 | 10 to 30 minutes |
| −40 to −47 | 5 to 10 minutes |
| −48 to −54 | 2 to 5 minutes |
| −55 or colder | under 2 minutes |
Worked example
20 F with a 15 mph wind: 15^0.16 = 1.5421, so WC = 35.74 + 12.43 − 55.13 + 13.19 = 6.2 F. In metric, −10 C with 20 km/h wind gives −17.9 C.
Frequently asked questions
What is wind chill?
Wind chill is how cold bare skin feels when wind strips heat away. At 20 F with a 15 mph wind it feels like 6.2 F. It does not change the real air temperature, and objects such as a car do not cool below it.
What formula is used?
The 2001 NWS and Environment Canada formula. In imperial units: 35.74 + 0.6215T - 35.75V^0.16 + 0.4275TV^0.16, with T in F and V in mph. In metric: 13.12 + 0.6215T - 11.37V^0.16 + 0.3965TV^0.16, with T in C and V in km/h. At -10 C and 20 km/h it gives -17.9 C.
How long until frostbite starts?
The bands follow the Environment Canada and NWS charts: 10 to 30 minutes from about -28 C wind chill, 5 to 10 minutes from -40 C, 2 to 5 minutes from -48 C and under 2 minutes from -55 C. At -30 C and 30 km/h the wind chill is -45.6 C, so 5 to 10 minutes. These are guides for healthy adults on exposed skin.
Why does it show a warning for mild or calm weather?
The formula was only fitted for air at or below 50 F (10 C) and wind of at least 3 mph (4.8 km/h). Outside that range the number can look nonsensical, for example a wind chill that is not meaningful in a light breeze at 60 F.