Sweat rate calculator

Track fluid in, food intake, urination, and environmental conditions to estimate gross sweat loss.

Session details
Duration
h min
Body weight (before → after)
→ kg
Environmental conditions
Air temperature
°C
Humidity
%
Wind force
Clothing
Heat training
Core body temperature
Average core temp
°C
Max core temp
°C

Optional — leave blank if not measured. Normal resting core temp ≈ 37°C; exercise typically raises this to 38–40°C.

Fluid intake
Drinks consumed
Water / plain drink
ml
Sports drink / gel fluid
ml
Food intake
Solid food eaten

Water content of food contributes ~0.6 ml per gram of solid food (mixed diet estimate).

Energy bars / gels / solids
g
Urination
Bathroom breaks
If you can't measure, each break defaults to 250 ml — a conservative average for exercise conditions. Edit any break to override.
Results
Total fluid in
—
ml
Urine output
—
ml
Weight loss
—
g → ml fluid
Gross sweat loss
—
ml
Sweat rate
—
ml / hr
Net fluid deficit
—
ml
% body weight lost
—
%
Dehydration level—
—
Formula: Gross sweat loss = weight loss (g→ml) + total fluid in − urine output. Net deficit = gross sweat loss − drinks consumed. 1 g body mass ≈ 1 ml fluid. Food water: 0.6 ml/g.

Session log