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Hydration Formula

Sweat Rate Formula

The Sweat Rate Formula helps you quantify the amount of fluid your body loses through sweat during exercise, which is crucial for developing a personalized hydration strategy. Understanding your sweat rate prevents dehydration and optimizes performance.

By Orbyd Editorial · AI Fit Hub Team
Best Next MoveRecovery

Sweat Rate Calculator

Calculate your personal sweat rate from pre/post-exercise weigh-ins and estimate fluid and sodium losses using ACSM guidelines.

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On This Page

Formula

Copy the exact expression or work through it step by step below.

Sweat Rate = (Pre Session Weight - Post Session Weight + Fluid Intake - Urine Output) / Hours Trained

Variables

SR

Sweat Rate

The sweat rate assumption used in the sweat rate calculation.

PSW

Pre Session Weight

The pre session weight value plugged into the sweat rate calculation.

PSW

Post Session Weight

The post session weight value plugged into the sweat rate calculation.

FI

Fluid Intake

The fluid intake value plugged into the sweat rate calculation.

UO

Urine Output

The urine output value plugged into the sweat rate calculation.

HT

Hours Trained

The hours trained value plugged into the sweat rate calculation.

Step By Step

  1. 1

    Set the baseline case with the real calculator inputs.

    Pre Weight Kg = 70, Post Weight Kg = 69.2, Duration Minutes = 60.0%, Fluid Consumed Ml = 500

  2. 2

    Translate rates, periods, and cash values onto the same footing before combining them.

    Keep the sweat rate assumptions consistent instead of mixing monthly and annual views.

  3. 3

    Apply the formula and read the first calculator outputs, not just the headline assumption.

    The calculator lands with sweat rate lper hr at 1.30% and total fluid lost l at 1.3.

  4. 4

    Run one changed scenario so the formula is stress-tested before it is trusted.

    The sweat rate calculator page is the fastest way to compare that second case.

Worked Example

Sweat Rate sample case

Pre Weight Kg

70

Post Weight Kg

69.2

Duration Minutes

60.0%

Fluid Consumed Ml

500

Sweat Rate = (Pre Session Weight - Post Session Weight + Fluid Intake - Urine Output) / Hours Trained using pre weight kg 70, post weight kg 69.2, duration minutes 60.0%, fluid consumed ml 500.

The calculator lands with sweat rate lper hr at 1.30% and total fluid lost l at 1.3.

Common Variations

Rate assumptions can be modeled as monthly, annual, gross, or net depending on the decision.
Scenario variants are useful because fixed assumptions rarely survive contact with real life unchanged.
Use Sweat Rate Calculator to compare the baseline result with one stressed case before relying on a single answer.

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Sources & References

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General fitness estimates — not medical advice. Consult a healthcare professional for medical decisions.