Wind Chill Calculator: How Cold Does It Feel?
Wind chill shows how cold the wind makes exposed skin feel. At 20 °F (−7 °C) with a 15 mph (24 km/h) wind it feels like about 6 °F (−14 °C).
It feels like
6.2°F
Frostbite risk: Low risk
13.8° colder than the air temperature
| Low risk | warmer than −28 °C (−18 °F) |
| Moderate risk | −28 to −39 °C (−18 to −38 °F): about 10–30 min |
| High risk | −40 to −47 °C (−40 to −53 °F): about 5–10 min |
| Very high risk | −48 to −54 °C (−54 to −65 °F): about 2–5 min |
| Extreme risk | −55 °C (−67 °F) or colder: under 2 min |
Cold, but the risk of frostbite is low. Dress in layers and cover exposed skin if you will be out for long.
Wind chill describes how fast exposed skin loses heat. It does not lower the real temperature, so objects such as cars and pipes never get colder than the air itself. The formula assumes walking pace in open, shaded conditions.
Show the math
- 1
Raise the wind speed to the power 0.16
15^0.16 = 1.5423
Wind cools you more, but with diminishing returns. The 0.16 power captures that curve.
= 1.5423
Read the steps as text
- Raise the wind speed to the power 0.16. 15^0.16 = 1.5423 Wind cools you more, but with diminishing returns. The 0.16 power captures that curve.
- Apply the wind chill formula. 35.74 + 0.6215 × 20 − 35.75 × 1.5423 + 0.4275 × 20 × 1.5423 = 6.2 This is the standard formula used by the US National Weather Service and Environment Canada.
- Compare with the air temperature. 20 °F air feels like 6.2 °F, which is 13.8° colder Cold, but the risk of frostbite is low. Dress in layers and cover exposed skin if you will be out for long.
What wind chill measures
Your body warms a thin layer of air next to your skin. Wind blows that layer away and pulls heat from you faster, so the same air temperature feels colder on a windy day. Wind chill is the calm-air temperature that would take heat from exposed skin at the same rate.
It describes how fast you lose heat, not the actual air temperature. A car or a water pipe will not cool below the real air temperature just because it is windy, although wind can make them reach that temperature faster.
The wind chill formula
This calculator uses the 2001 formula adopted by the US National Weather Service and Environment Canada: WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275T × V^0.16, with T in °F and V in mph. The 0.16 power reflects that each extra bit of wind matters less than the last. If you use Celsius or km/h, the calculator converts first and shows that step.
The formula only applies when the air is 50 °F (10 °C) or colder and the wind is at least 3 mph (5 km/h). Outside that range the calculator tells you why there is no wind chill.
Wind chill and frostbite
As a guide, at a wind chill of about −28 °C (−18 °F) exposed skin can freeze in 10 to 30 minutes. At −40 °C it can take 5 to 10 minutes, at −48 °C about 2 to 5 minutes, and at −55 °C or colder under 2 minutes. The table under the result highlights your level.
Cover exposed skin, wear layers with a windproof outer shell, keep hands, feet and ears warm, and come inside if skin turns numb or waxy. The formula assumes an adult walking in the open, so real risk varies with clothing, sunshine, exertion and health.
Frequently asked questions
- How do you calculate wind chill?
- Use WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275T × V^0.16 with temperature in °F and wind in mph. The calculator does the conversions and the arithmetic and shows each step.
- Does wind chill make the temperature actually drop?
- No. It measures the cooling effect on exposed skin. Objects do not fall below the real air temperature.
- Why is there no wind chill in warm or calm weather?
- The formula is only valid at 10 °C (50 °F) or below and with wind of at least 5 km/h (3 mph). Outside that, wind has little cooling effect worth reporting.
- What wind chill causes frostbite?
- Frostbite risk rises below about −28 °C (−18 °F), where exposed skin can freeze in 10 to 30 minutes. It gets faster as it gets colder.