Sauna Heat-Dose Calculator
The famous sauna longevity data has specific numbers attached: 4–7 sessions a week, ~19+ minutes, ~174°F. Score your actual habit against them — including the infrared adjustment most calculators skip.
Not medical advice. Skip the sauna with fever or after alcohol; pregnant readers and anyone with cardiovascular conditions should clear heat exposure with a doctor. Stand up slowly — heat plus dehydration drops blood pressure.
What "effective dose" means here
The cohort studies used traditional saunas around 174°F. Infrared cabins top out near 130–140°F, where the same minutes deliver a smaller heat load. The calculator scales your minutes by temperature relative to the study conditions, so "45 minutes of infrared" and "20 minutes of Finnish sauna" land in comparable territory instead of looking identical on paper.
Shopping with this in mind matters: a cabin that only reaches 140°F isn't bad, it just needs longer sessions. We flag the real temperature ceiling on every pick in our home sauna rankings.
Frequently asked questions
How many times a week should I sauna?
The Finnish cohort research (Laukkanen 2015, ~2,300 men over 20 years) found the largest reduction in cardiovascular mortality among people using a sauna 4–7 times per week, with sessions of about 19 minutes or longer at roughly 174°F. Two to three sessions a week still showed meaningful benefit over one.
How long should a sauna session be?
The benefit threshold in the cohort data sits around 19–20 minutes per session in a traditional ~174°F sauna. Infrared cabins run cooler (120–140°F), so plan 30–45 minutes for a comparable heat load.
Do infrared saunas count toward the research numbers?
The mortality studies were done with traditional Finnish saunas at 170°F+. Infrared raises core temperature more slowly at lower air temps, so most practitioners extend sessions to 30–45 minutes. The calculator adjusts your effective dose by temperature for exactly this reason.
How much water should I drink after a sauna?
A typical session costs 0.5–1 liter of sweat — roughly 16–32 oz. Weigh yourself before and after once: every pound lost is about 16 oz of fluid to replace, ideally with electrolytes after longer or repeated sessions.