Sweat Rate Calculator
Your sweat rate changes based on temperature, humidity, airflow, and exercise intensity. As you exercise in different conditions, use the calculator below to establish personalized sweat rates for different training and event scenarios.
Sweat Rate
Calculator
Weigh in, train, weigh out. Based on Asker Jeukendrup's method for estimating fluid loss during exercise.
Estimated sweat rate
— L / hour
Fill in all four sections to see your hourly sweat rate.
01 Body weight
Empty your bladder and weigh in nude before exercise, then towel dry and weigh out the same way after.
02 Fluid intake
How much you drank during exercise — track it as you go, or weigh your bottle before and after (1 g ≈ 1 mL).
03 Urine loss
Measure urine directly if you can — otherwise a single bathroom visit is estimated at about 0.3 L.
Didn't measure?
04 Duration
How long you exercised for.
Sweat rate = (C + Z − U) ÷ D → (weight loss + fluid drunk − urine) ÷ hours
Based on the method described in Asker Jeukendrup's
“How much do you sweat?” — mysportscience.com
This gives an estimate, not a lab-precise measurement. Take a few readings across different conditions for a fuller picture.
Optimize Your Hydration Strategy With a Sweat Test
We've partnered with Precision Fuel & Hydration to offer a non-invasive, zero-effort assessment designed to unlock the unique composition of your sweat. You'll discover your body's specific sweat sodium concentration, a crucial piece of the puzzle in building your hydration strategy. The Sweat Test is done at rest, so there's no treadmill or exercise bike, no sweat, and absolutely no needles.
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