Windchill calculator for iPhone, with frostbite risk
Last updated 2 June 2026
Yes. Ferdinands Outdoor Companion (FOC) includes an offline windchill calculator: set the air temperature and wind speed, and it returns the real-feel temperature using the standard wind chill formula, then sorts the result into a frostbite-risk band. The formula applies when the temperature is at or below 10 C and the wind is at or above 4.8 km/h, the range where wind chill is meaningful. Below that, it just shows the air temperature. It works fully offline, with no ads and no tracking.
How the windchill calculator works
You set two values with sliders: air temperature (from -40 C up to 10 C) and wind speed (from 5 up to 100 km/h). FOC then applies the standard wind chill formula used by Environment Canada and the US National Weather Service to give a feels-like temperature in degrees Celsius. The formula is only valid in the cold-and-windy range, at or below 10 C and at or above 4.8 km/h, so outside that range the calculator simply reports the plain air temperature rather than a misleading number. Everything runs on the device, so it works in airplane mode with no signal.
From real-feel to frostbite risk
FOC does not stop at a number. It grades the feels-like result into five frostbite-risk bands: minimal, low, moderate, high, and extreme. For the more serious bands it adds an approximate time-to-frostbite on exposed skin, roughly 30 minutes at moderate, 10 minutes at high, and 5 minutes at extreme. It also shows short cold-weather reminders about layering, protecting your extremities, and keeping moving. These are guidance to support your judgement, not a guarantee. Dress for the real feel, not the thermometer, and turn back when conditions exceed your gear and experience.
How it compares
| Factor | FOC | By hand |
|---|---|---|
| Works with no signal | Yes | Yes |
| Applies the standard formula for you | Yes | You do the math |
| Grades frostbite risk into bands | Yes, five bands | No |
| Shows time-to-frostbite for serious cold | Yes | No |
| Ads or tracking | None | None |
| Price | Free | Free |
Frequently asked questions
Is there an offline windchill calculator for iPhone?
Yes. Ferdinands Outdoor Companion (FOC) has a windchill calculator that runs fully on the device, so it works in airplane mode with no signal.
What windchill formula does FOC use?
The standard wind chill formula used by Environment Canada and the US National Weather Service. It is valid when the temperature is at or below 10 C and the wind is at or above 4.8 km/h. Outside that range FOC shows the plain air temperature.
What are the frostbite-risk bands?
FOC grades the feels-like result into five bands: minimal, low, moderate, high, and extreme. For the serious bands it adds an approximate time to frostbite on exposed skin, roughly 30, 10, and 5 minutes.
What temperature and wind ranges can I set?
Air temperature from -40 C up to 10 C, and wind speed from 5 up to 100 km/h, both with sliders.
Is the FOC windchill calculator free?
Yes. FOC is free with no ads, no in-app purchases, and no tracking, and the calculator works fully offline on iPhone.
Related
Sources
This is general reference, not medical, safety, or professional advice. Skills like first aid and foraging carry real risk. In a real emergency, call your local emergency number (112 in the EU, 911 in the US).