Frostbite Time Calculator
Wind chill and frostbite minutes from cold and wind.
What it does
Wind steals heat faster than cold alone: 0 F air at 20 mph bites like -22 still air with 30 minutes to frostbite. Charts band the danger by chill, not temperature.
The tool above takes air temp with wind in imperial or metric. It returns wind chill with frostbite minutes and cover guidance.
The default 0 F with 20 mph reads -22 F for 30 minutes. The metric mirror at -18 C with 32 km/h reads -30 C, and -20 F with 30 mph reads -53 F for 5 minutes.
Weather service charts publish the wind chill formula with frostbite time bands beside it. Canadian programs mirror the same chart zones for northern winters.
Bands guide clothing, not courage: cover every gap, watch white waxy skin, and warm gradually without rubbing. Warnings rule outings; arithmetic only explains them.
How to use
- Pick F or C units.
- Type air temp.
- Type wind speed.
- Read wind chill first.
- Read minutes beside it.
- Cover all skin gaps.
Formula
- temp
- Air temp in F or C.
- wind
- Wind in mph or km/h.
- time
- Minutes to exposed frostbite.
Weather service wind chill programs publish the standard formula with frostbite time bands on the same charts. Canadian weather services mirror the program with matching bands. Metric inputs convert to F and mph first, then report Celsius back.
Worked example
Example: zero with wind
Imperial defaults: 0 F, 20 mph wind.
- Air: 0 F with 20 mph wind.
- Chill: 35.74 + 0 minus 35.75x20^0.16 + 0 = -22 F.
- Band: -25 to -10 reads 30 min.
- Cover: all skin, no gaps.
- Metric: -18 C with 32 km/h reads -30 C.
- Tool shows -22 F, 30 min, Cover all skin.
Reference table
| Chill | Time | Action |
|---|---|---|
| Over -10 F | Over 30 min | Dress warm |
| -25 to -10 F | 30 min | Cover gaps |
| -40 to -25 F | 10 min | Limit exposure |
| Under -40 F | 5 min | Stay inside |
Common mistakes
Try it yourself
Quick checks. Answers sit tucked under each question.
Minus 20 F, 30 mph?
-53 F with 5 minutes: cover all skin at once.
Minus 18 C, 32 km/h?
-30 C with 30 minutes in metric.
Wind 1 mph?
Under 3 mph reads calm air math: enter wind from 3 up.
Questions
Wind chill formula?
35.74 + 0.6215T - 35.75V^0.16 + 0.4275TV^0.16 in F and mph. Metric converts first.
Frostbite bands?
Over 30, 30, 10, then 5 minutes across -10, -25, -40 band edges.
Wet and gaps?
Yes, wet skin, wind gaps, and metal touch all accelerate freezing.
Feels like enough?
No, thermometers rule frostbite while feels like guides comfort.
First signs?
Yes, face, fingers, and toes first. White waxy skin needs warming, not rubbing.
Stay out by math?
No, this screens bands. Warnings and clothing rule safety, never arithmetic.