Wind Chill Calculator
Calculate the wind chill 'feels like' temperature and frostbite risk.
About Wind Chill Calculator
Wind chill describes how cold the air feels on exposed human skin due to the wind's convective heat loss. Moving air strips away the thin warm layer of air next to skin faster than calm air does, making the effective temperature feel colder. The NWS 2001 formula was developed from human trials where subjects walked outdoors at various temperatures and wind speeds, replacing the earlier 1945 formula that was derived from water-bottle experiments and consistently over-predicted the chill. The formula is valid only at or below 50°F (10°C) and at wind speeds above 3 mph (4.8 km/h); outside those bounds it produces unreliable results.
Formula
NWS 2001 Wind Chill (°F, mph)
Wind Chill = 35.74 + 0.6215 × T − 35.75 × V^0.16 + 0.4275 × T × V^0.16
- T
- Air temperature in °F
- V
- Wind speed at 10 m height in mph
- WC
- Wind chill index in °F
Worked example
With the default values below, Wind Chill Calculator returns Wind Chill (°F) of 6.2. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Unit Systemone of Imperial (°F / mph), Metric (°C / km/h)
- Imperial (°F / mph)
- Air Temperature (°F)accepts -80–50
- 20
- Wind Speed (mph)accepts 3–120
- 15
- Air Temperature (°C)accepts -62–10
- -7
- Wind Speed (km/h)accepts 5–193
- 24
Results
- Wind Chill (°F)The 'feels like' temperature accounting for wind cooling.
- 6.2
- Wind Chill (°C)
- -14.3
- Effective Temperature Drop (°F)
- 13.8
- Frostbite RiskBased on NWS exposure-time thresholds.
- Low — minimal frostbite risk under normal exposure.
Step by step
- 1Inputs (normalised to °F, mph)= T = 20°F, V = 15 mph
- 2Compute V^0.16= 1.5423
- 3Apply NWS 2001 formula= 6.2°F (-14.3°C)
- 4Effective temperature drop= 13.8°F (7.6°C)
- 5Frostbite risk= Low — minimal frostbite risk under normal exposure.
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why does the calculator refuse inputs above 50°F or below 3 mph?
The NWS 2001 formula was derived from experiments conducted in cold conditions with meaningful airflow. Extrapolating it to warm temperatures or calm air produces numbers that don't reflect actual cooling on human skin. Above 50°F, wind may feel pleasant but the formula would give a lower temperature than the air, which can mislead you into under-dressing.
What is frostbite risk based on?
The NWS frostbite risk bands are based on military and medical research into the time required for exposed skin to freeze. At −19°F wind chill, frostbite can occur in 30 minutes; at −38°F in 10 minutes; at −50°F in 5 minutes. These are guides, not guarantees — wet skin, prior cold injuries, and reduced circulation lower these thresholds.
Does wind chill affect the temperature of objects?
No. Wind chill only applies to warm objects losing heat, like skin. It does not affect how cold a car engine gets, whether water pipes freeze, or whether a thermometer reads lower. A thermometer in the wind reads the true air temperature — the same number as a sheltered thermometer.
Why does the formula use mph even for the metric version?
The NWS formula was published in US customary units (°F, mph). Converting inputs to °F and mph, computing the result, then converting back to °C is more accurate than using a metric reformulation, which introduces rounding. This calculator does exactly that conversion transparently.