Sweat Rate Calculator
Sweat Rate Calculator 💧
What is sweat rate?
Sweat rate is how much fluid you lose per hour of exercise. It varies a lot between people, and even between sessions for the same person depending on heat, humidity, and intensity - so a generic hydration guideline is really just a guess. Weighing yourself before and after a session tells you what your body actually lost, which is a much better basis for planning fluid intake on similar future sessions.
How to Use This Calculator:
- Right before training, weigh yourself naked (or in the same minimal, dry kit you'll weigh in again after) while holding every bottle/flask you're taking with you, full.
- Train as normal, drinking from those same bottles as you normally would.
- Straight after, weigh yourself again the same way - naked or in that same dry kit (towel off first), still holding those same bottles (now emptier), before eating, drinking anything else, or refilling.
- Enter both weights and how long the session lasted.
This is a simple home protocol, not a lab-grade sweat test - a rough, useful guide to your fluid loss, not a precise one. It treats 1kg of weight lost as 1L of sweat, and doesn't separately account for food mass or bathroom breaks during the session. It also can't tell you anything about your sweat sodium concentration, which varies hugely between athletes and matters a lot for electrolyte planning on longer or hotter sessions.
For the full picture, including sodium loss data, Andy at Tritanium Coaching offers proper sweat testing.
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