Sauna

Sauna hydration calculator

Estimate fluid to replace after sauna sessions, hot tubs, steam rooms, and repeated heat rounds.

A sauna session can easily cost 300-800 ml of sweat depending on heat, duration, and body size. Replace it steadily after the session instead of chugging during heat exposure.

Minutes in heatTotal sauna or steam time

minutes

Effort / sweatAdjusts the buffer

Already replacedOptional

Bottle sizeFor tracking

Extra fluid estimate

0.5litres

About 15 oz total, or 0.9 bottles over 30 minutes.

Pace

900 ml

per hour

Left

0.5 L

0.9 bottles

Electrolytes

Optional

today

When to use electrolytes

Electrolytes can help after repeated rounds, very heavy sweat, or sauna after training. For one short session, water plus food is usually enough.

Safety note

Avoid alcohol around sauna, leave if dizzy or unwell, and follow clinician guidance if you have heart, blood pressure, kidney, or pregnancy-related concerns.

Drink a little before the session.

Replace most fluid after cooling down.

Pair longer sessions with food or electrolytes.

Frequently asked

Should I drink during sauna?

Small sips are fine, but most replacement should happen before and after. Leaving the heat to cool down matters more than trying to out-drink sweat.

Can sauna dehydrate me?

Yes. Sauna increases sweat loss quickly, especially with repeated rounds, high heat, alcohol, or exercise beforehand.