Sweat rate test analyzer
Use a simple before-and-after field test to estimate how much fluid you lost in that session.
Personal hydration planner
Turn a sweat-rate test into a planning range for a similar session, without a one-size-fits-all drinking rule.
Personal hydration planner
Example valuesTurn a sweat-rate test into a planning range for a similar session, without a one-size-fits-all drinking rule.
No account needed. Calculations happen in your browser; your entries are not saved or sent to Century.
Example · Estimated fluid-loss range
0.9–1.6L
A scenario from a sweat test in comparable conditions, not a drinking prescription.
- Projected sweat loss
- 1.60 L
- Lower edge per hour
- 0.45 L/h
How it’s calculated
Projected sweat loss = measured sweat rate × planned duration. The lower edge of the fluid planning envelope is max(0, projected loss − body mass × chosen maximum mass-loss percentage). The upper edge equals projected sweat loss, since replacing more than measured loss risks net fluid gain. This is a scenario, not a directive to drink a fixed amount; thirst, conditions and individual medical advice matter.
Reference: National Athletic Trainers' Association: Fluid replacement
For general wellness information. This tool does not diagnose health conditions or replace medical advice.
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Personal hydration planner: use your own data
What to enter
Turn a sweat-rate test into a planning range for a similar session, without a one-size-fits-all drinking rule.
Sweat rate changes with heat, clothing and intensity. The range illustrates a body-mass-loss scenario while avoiding a suggestion to drink more than the projected sweat loss.
Read the result in context
Projected sweat loss is 1.6 L. A 1% mass-loss allowance is 0.7 L, so the fluid planning envelope starts at 0.9 L and ends at 1.6 L.
It may be a poor estimate. Repeat a test under conditions and intensity close to the planned session.
Where this estimate stops
A fluid-volume estimate does not reveal sweat sodium concentration or individual electrolyte needs.
See workouts and recovery together in Century.
Frequently asked questions
How do I get my sweat rate?
Use a comparable session in the sweat-rate test analyzer. Weigh yourself before and after, record fluid consumed and urine passed, and divide estimated sweat loss by session duration.
Why is this a range rather than one drinking target?
Sweat rate changes with heat, clothing and intensity. The range illustrates a body-mass-loss scenario while avoiding a suggestion to drink more than the projected sweat loss.
Can I use a test from a cool run for a hot race?
It may be a poor estimate. Repeat a test under conditions and intensity close to the planned session.
Does this estimate sodium needs?
No. A fluid-volume estimate does not reveal sweat sodium concentration or individual electrolyte needs.