Exercise Hydration Calculator
Fluid to drink per hour from your sweat rate.
Enter your values
ⓘ Live results
Results
- Sweat rate
- 1,200 ml/hour
- Total fluid lost
- 1,800 ml
- Drink during exercise
- 960 ml/hour
- Post-session replacement
- 2,700 ml
Quick answer
Sweat rate is weight lost during exercise plus fluid drunk, divided by hours. Replace 100-150% of losses afterwards.
sweat rate = (weight lost + fluid drunk) / hours
How to use the Exercise Hydration Calculator
- 1Weigh yourself without clothes before and immediately after a session.
- 2Record everything you drank during it.
- 3Aim to lose no more than 2% of body weight per session.
Worked example
Using the values the calculator loads with:
Inputs
- Weight before74.5 kg
- Weight after73.2 kg
- Fluid drunk500 ml
- Duration1.5 h
Results
- Sweat rate1,200 ml/hour
- Total fluid lost1,800 ml
- Drink during exercise960 ml/hour
- Post-session replacement2,700 ml
Frequently asked questions
Do I need electrolytes?
Above one hour of hard sweating, sodium replacement helps absorption and prevents cramping.
Can I drink too much?
Yes — hyponatraemia is dangerous. Do not drink beyond your sweat rate.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.