NUTRITION & PHYSIOLOGY

Sweat Rate
Calculator

Estimate your hourly sweat rate by comparing pre- and post-exercise body weight, accounting for fluid intake during the session. Use the results to plan your hydration strategy for training and racing.

Inputs

Pre-exercise weight

Post-exercise weight

Fluid consumed during exercise

Duration

min

Results

Sweat Rate

1,300 ml/hr

hourly fluid loss

Total fluid lost 1,300 ml

Body weight lost 1.14%

Dehydration status Mild dehydration

Aim to drink 325 ml every 15 minutes during exercise.

% Body Weight Lost	Status
< 1%	Well hydrated
1 – 2%	Mild dehydration
2 – 3%	Moderate dehydration
3 – 4%	Significant dehydration
> 4%	Severe dehydration

Methodology

Total fluid lost = (Pre-weight − Post-weight) × 1000 + Fluid consumed
Sweat rate = Total fluid lost ÷ (Duration ÷ 60)
% Body weight lost = (Pre-weight − Post-weight) ÷ Pre-weight × 100

Weight change is assumed to represent fluid loss only. For best accuracy, weigh yourself nude or in dry clothing before and after exercise, and account for any urination during the session. The 15-minute drinking recommendation divides the hourly sweat rate into four equal portions.

Sweat RateCalculator

Sweat Rate
Calculator