Sweat Rate Calculator
Sweat rate (L/hr) = (pre-weight − post-weight + fluid intake) / duration.
Result
Sweat rate
1.50 L/hr
1,500 mL/hr · replace ~80% during, top up after.
- Weight change1.00 kg (1.00 kg)
- Sweat from weight1,000 mL
- Fluid drunk500 mL
- Urine/waste0 mL
- Total sweat1,500 mL
- Duration60 min
- Sweat rate1,500 mL/hr (1.50 L/hr)
Step-by-step
- Weight loss = 70 − 69 = 1.00 kg (≈ 1,000 mL of fluid).
- Total sweat = weight loss + fluid drunk − urine = 1,000 + 500 − 0 = 1,500 mL.
- Rate = total / hours = 1,500 / 1.000 = 1,500 mL/hr.
How to use this calculator
- Weigh yourself nude before exercise.
- Log every mL of fluid consumed during.
- Weigh again after exercise (towel off, nude).
- Calculate; aim to replace 60-80% during, finish hydrating after.
About this calculator
Sweat rate measures fluid loss per hour: the foundation of hydration strategy. Typical recreational athletes lose 500-800 mL/hr; competitive athletes 1.0-1.5 L/hr; elite endurance athletes in heat 2.0-2.5 L/hr. Replace 60-80% during exercise (more isn't absorbed). Losing >2% of body weight as sweat impairs performance. To measure: weigh nude before and after a 60-90 min effort, log everything drunk and any urine.
Frequently asked
Sweat-soaked clothes hold ~200-500g of water — would under-count sweat loss. Towel off, weigh nude.
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