Health & Fitness
Cycling Sweat Rate & Hydration Calculator
Updated Aug 27, 2026 Reviewed Aug 27, 2026
Calculate sweat loss and hourly sweat rate from pre/post weight, fluid intake, urine and duration, then scale a user-selected replacement plan.
Measured sweat test and ride planning
Use a representative pre/post ride test
Result
Calculation summary
Enter values to see the result
Your result, breakdown, assumptions, and warnings will appear here.
Live hydration preview
Measure losses before scaling a plan
Measured sweat rate
0.9 L/h
Selected plan fluid
2,160 ml
Whole bottles
3
Body-mass change is corrected for drinking and urine, then converted to a condition-specific hourly sweat rate.
How to use this calculator
- 1Weigh immediately before and after a representative ride.
- 2Enter all drink, urine and exact duration.
- 3Choose a future duration and replacement percentage.
Formula
sweat L ≈ pre kg − post kg + drink L − urine L
Rate divides test loss by hours and scales it to a future ride.
Calculation steps
- Convert units.
- Adjust mass loss for drink and urine.
- Scale rate and round bottles upward.
Worked example
A 0.6 kg loss plus 0.75 L drink over 90 minutes implies 0.9 L/h.
Assumptions
- 1 kg acute change approximates 1 L water.
- Food and clothing moisture are excluded.
- Rate is condition specific.
- Sodium is loss only, not a prescription.
Sources
Frequently asked questions
Should I replace 100%?
Not automatically; needs are individualized and overdrinking is dangerous.
Why repeat tests?
Conditions and intensity change sweat rate.
What if weight rises?
The tool flags possible intake beyond net loss.
Does this prescribe sodium?
No; it only estimates loss from an entered measurement.
Related calculators
Cycling Fueling & Energy Planner
Estimate energy from power or manual calories, set a carbohydrate target, combine drinks and food, and fill the remainder with whole gels.
Cycling Route Power & Time Planner
Plan up to twelve cycling route segments with distance, grade, target power, wind and rolling resistance to estimate speed, time, work and elevation.