Sweat Rate Calculator
Calculate sweat rate from pre- and post-run weight for hydration planning.
How runners use this tool
Sweat rate testing turns a simple weigh-in protocol into liters-per-hour fluid targets you can use in training and on race day.
- Weigh yourself before and after a representative run.
- Record fluid consumed during the run and total duration.
- Use the sweat rate result to plan hourly drinking for similar conditions.
How to use the result
- Pair sweat rate with marathon fueling targets for long races.
- Re-test in hotter weather before warm-weather goal races.
Formula and assumptions
- Sweat rate changes with pace, clothing, humidity, and heat acclimation.
- One test is a starting point; repeat tests improve reliability.
Worked examples
- Beginner: 1-hour easy run test → Hourly sweat rate in L/hour. Replaces generic hydration advice with your data.
- Race prep: Warm long run rehearsal → Higher fluid target band. Improves race-day drinking plan.
- Advanced: Compare cool vs hot sessions → Condition-specific sweat rates. Shows why one bottle plan fails across seasons.
Related searches: sweat rate calculator, running sweat rate, sweat rate test, hydration sweat rate.
Common questions
How should runners interpret Sweat Rate Calculator results?
Pair sweat rate with marathon fueling targets for long races.
When is this estimate less reliable?
Sweat rate changes with pace, clothing, humidity, and heat acclimation.
Should beginners use Sweat Rate Calculator?
Yes. Start with conservative assumptions, then refine inputs as you collect consistent training data.
What tool should I use next after this result?
Use the related tools section to move from one calculation into pacing, training, fueling, and full plan execution.