Wind Chill Calculator
How cold it feels from air temperature and wind speed, using the NWS formula.
Results update as you type.
About this calculator
Wind chill is how cold the air actually feels on exposed skin once moving air is factored in, because wind strips away the thin insulating layer of warmed air around the body and speeds up heat loss. This wind chill calculator uses the current U.S. National Weather Service formula (adopted in 2001): in imperial units, WC(°F) = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275T·V^0.16, with T the air temperature in °F and V the wind speed in mph; the metric version, WC(°C) = 13.12 + 0.6215T − 11.37V^0.16 + 0.3965T·V^0.16, uses °C and km/h.
As a worked example, an air temperature of 20 °F with a 15 mph wind feels like about 6 °F — roughly 14 degrees colder than the thermometer reads. Raise the wind and the chill deepens, but with diminishing returns, since the V^0.16 term flattens out at high wind speeds. The calculator shows the feels-like temperature, how much colder that is than the actual air, and a table of wind chills across a range of wind speeds so you can see the trend.
The formula is only defined for cold, breezy conditions — at or below 50 °F (10 °C) and winds above about 3 mph (5 km/h) — so above those the "feels like" simply equals the air temperature. Beyond comfort, wind chill matters because it governs how fast exposed skin can freeze: the tool flags frostbite risk, which becomes serious once the wind chill drops below about −18 °C (0 °F) and can freeze skin in under 30 minutes in extreme cold.
Frequently asked questions
What is the wind chill formula?
The NWS formula (2001) in imperial units is WC = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275T·V^0.16, with T in °F and V in mph. It models heat loss from bare skin as wind strips away the thin warm layer around the body.
When does wind chill apply?
It is defined for temperatures at or below 50 °F (10 °C) and winds above about 3 mph (5 km/h). Above those, wind has little cooling effect and the "feels like" equals the air temperature.
How fast can frostbite occur?
When the wind chill drops below roughly −18 °C (0 °F) frostbite becomes a risk, and below about −28 °C (−19 °F) exposed skin can freeze in 30 minutes or less — sooner in more extreme wind chills.
Does wind chill affect objects, or only people?
Only living, warmer-than-air things. Wind chill measures how fast a warm body loses heat, so it makes people and animals feel colder, but it cannot cool an object like a car or a water pipe below the actual air temperature.
Why does more wind not keep making it feel proportionally colder?
The formula uses wind speed to the power 0.16, which rises steeply at first and then flattens. Going from 5 to 15 mph drops the feels-like temperature a lot, but going from 40 to 50 mph changes it only slightly.
Does the calculator work in both °F/mph and °C/km/h?
Yes. Pick imperial to enter °F and mph or metric for °C and km/h, and it applies the matching NWS equation. The frostbite thresholds are judged on the metric scale internally so both unit systems agree.
At what temperature does wind chill stop mattering?
Above 50 °F (10 °C), or when the wind is below about 3 mph (5 km/h), wind has little cooling effect and the feels-like temperature equals the air temperature — so the calculator returns a note rather than a lower number in those conditions.
API — use this calculator from code
Call this calculator as a free JSON endpoint — no key required. Send the field values below as query parameters or JSON. Read the full API docs →
Endpoint
GET https://calculator.free/api/v1/wind-chill/curl
curl "https://calculator.free/api/v1/wind-chill/?units=imperial&temp=20&wind=15"JavaScript fetch()
const r = await fetch(
"https://calculator.free/api/v1/wind-chill/?" + new URLSearchParams({
"units": "imperial",
"temp": "20",
"wind": "15"
}));
const data = await r.json();
console.log(data.results);Results are estimates for general guidance only, not financial, medical or tax advice.