Wind Chill Calculator.

Formula and practical context.

Formula, variables, and method

wind chill °F = 35.74 + 0.6215T − 35.75V^0.16 + 0.4275TV^0.16. T is Fahrenheit and V is miles per hour; output is also converted to Celsius. Wind chill estimates the equivalent cooling effect on exposed skin from low air temperature and wind. Start by identifying what each entered number represents and whether it is a measured value, a specification, or an assumption. Convert units before combining quantities, preserve full precision through intermediate steps, and round only the displayed result. Normalize to °F and mph, apply the wind-speed exponent 0.16 in the NWS equation, and convert the apparent temperature back to Celsius. This sequence makes the output reproducible and helps expose a misplaced unit or decimal point before it affects a decision.

Worked example and independent check

At 0 °F with wind at 15 mph, the NOAA/NWS formula gives a wind chill near −19.4 °F. To check the example independently, write the formula first, substitute the values with their units, and complete one operation at a time. Compare the order of magnitude with a familiar reference rather than accepting a formatted result automatically. Normalize to °F and mph, apply the wind-speed exponent 0.16 in the NWS equation, and convert the apparent temperature back to Celsius. If a second method or inverse calculation is available, use it to recover an original input. Small differences from hand calculation should come only from displayed rounding, not from a different definition.

Units and result interpretation

Temperature may be entered in Fahrenheit or Celsius and wind in mph or km/h; the official US formula is evaluated with °F and mph. Wind chill estimates the equivalent cooling effect on exposed skin from low air temperature and wind. A unit is part of the quantity, not a label added after the arithmetic. Keep decimal and binary prefixes, temperature scales, elapsed-time units, and electrical prefixes explicit. When comparing two scenarios, change one assumption at a time and retain the same unit convention. The result describes only the relationship named by this calculator; it does not automatically establish capacity, safety, compatibility, quality, or compliance.

Validation and boundary cases

The formula applies at 50 °F or colder and wind above 3 mph; warmer or calmer inputs receive an applicability error. Blank values, malformed text, non-finite numbers, impossible ranges, zero divisors, and unsupported combinations receive an explicit message rather than a silent fallback. Boundary values are checked before the formula runs. If an input comes from a specification sheet, weather report, network plan, or measurement instrument, confirm its definition and precision. A syntactically valid value can still be unsuitable for the real situation, so inspect the assumptions alongside the result.

Assumptions, privacy, and practical limits

Sun, shelter, wet clothing, exposure duration, activity, individual health, and local warnings are not represented; frostbite risk requires official guidance. All entered values are processed in the browser and are not sent to a calculation service. Use the result as a transparent estimate or transformation, keep the source values with any saved result, and consult the linked authoritative material for definitions and applicability. For safety-critical, health-adjacent, security, network, chemical, or electrical work, verify the result with current standards, official warnings, qualified professionals, and appropriate test equipment.

Check assumptions and sources.

Sun, shelter, wet clothing, exposure duration, activity, individual health, and local warnings are not represented; frostbite risk requires official guidance.

NOAA/NWS Wind Chill Chart