Athlete Sweat Rate (L/hr), Dehydration % & Sodium Electrolyte Replacement Calculator

Compute hourly sweat loss (L/hr), % body weight lost, and sodium mg/hr replacement.

Hourly Exercise Sweat Rate
1.48 L/hr
Hourly Sodium Lost in Sweat 1,406 mg Na+/hr
Net Body Mass Dehydration % (Keep <2%) 1.64 %
Post-Workout Rehydration Target (150%) 1.8 Liters
Inputs
⚡ Scenarios:
kg
Nude/minimal-clothing weight before exercise (kg).
kg
Weight immediately after exercise (toweled dry, kg).
mL
Total water/sports drink consumed during the session (mL).
min
Total exercise duration in minutes.
mg/L
Sweat sodium concentration (500 mg/L low, 950 mg/L average, 1,500 mg/L salty sweater).
Results & Graph
Hourly Exercise Sweat Rate
1.48 L/hr
Hourly Sodium Lost in Sweat
1,406 mg Na+/hr
Net Body Mass Dehydration % (Keep <2%)
1.64 %
Post-Workout Rehydration Target (150%)
1.8 Liters

Hourly Exercise Sweat Rate

Graph 1 • Sweat Rate & Sodium Loss • Domain Architecture & Live Telemetry Maps Pre Exercise Weight Kg, Post Exercise Weight Kg, Fluid Consumed During Ml through Sweat Rate & Sodium Loss Formula.
Sweat Rate & Sodium Loss • Clinical & Physiological Reference Scale Low / Baseline Target / Reference Elevated / Watch High / Action Hourly Exercise Sweat Rate: 1.48 L/hr Hourly Sodium Lost in Swea 1,406 mg Na+/hr Net Body Mass Dehydration 1.64 % Post-Workout Rehydration T 1.8 Liters
Graph 2 • Hourly Exercise Sweat Rate Across Pre Exercise Weight Kg Sweep (40% → 160%) Evaluates TotalSweatLoss_L = (PreWeight_kg − PostWeight_kg) + FluidDrank_L; Swea across 7 operating points (current input highlighted).
0 L/hr 20.09 L/hr 40.17 L/hr 0.0400 29.20kg 0.0400 43.80kg 0.0400 58.40kg 1.48 73kg 13.16 87.60kg 24.84 102.2kg 36.52 116.8kg
Graph 3 • Joint Sensitivity: Pre Exercise Weight Kg × Post Exercise Weight Kg Compares Hourly Exercise Sweat Rate when Post Exercise Weight Kg is shifted +25% (solid) vs. −25% (dashed).
0 L/hr 18.35 L/hr 36.70 L/hr --- Post Exercise Weight Kg @ 75% 0.0400 -30% 0.0400 -15% 0.0400 +0% 0.0400 +15% 4.64 +30%
Summary: Total fluid lost is 1.85 L (1.48 L/hr or 1480 mL/hr), net body mass dehydration is 1.64%, and hourly sodium loss is 1406 mg/hr.
Summary: Total fluid lost is 1.85 L (1.48 L/hr or 1480 mL/hr), net body mass dehydration is 1.64%, and hourly sodium loss is 1406 mg/hr.
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Interactive chart & math engine powered by CalculatorGraph

Formula & Mathematical Methodology: Sweat Rate & Sodium Loss Formula

TotalSweatLossL = (PreWeightkg − PostWeightkg) + FluidDrankL
SweatRateLhr = TotalSweatLossL / Durationhrs
TotalSweatLoss_L = (PreWeight_kg − PostWeight_kg) + FluidDrank_L; SweatRate_L_hr = TotalSweatLoss_L / Duration_hrs
  • preExerciseWeightKg: Pre Exercise Weight Kg (kg)
  • postExerciseWeightKg: Post Exercise Weight Kg (kg)
  • fluidConsumedDuringMl: Fluid Consumed During Ml (mL)
  • exerciseDurationMinutes: Exercise Duration Minutes (min)
  • sweatSodiumConcentrationMgL: Sweat Sodium Concentration Mg L (mg/L)

Rounding: Clinical scores round to statutory integer or decimal precision; physiological metrics round to 2 decimal places.

Worked Example: Clinical / Physiology Scenario: Sweat Rate & Sodium Loss

Compute hourly sweat loss (L/hr), % body weight lost, and sodium mg/hr replacement.

  1. Enter lab values, anthropometric measurements, or performance test metrics.
  2. Evaluate the reference equation: TotalSweatLoss_L = (PreWeight_kg − PostWeight_kg) + FluidDrank_L; SweatRate_L_hr = TotalSweatLoss_L / Duration_hrs.
  3. Inspect the primary classification, supporting indices, and 3 SVG charts.
Result: Computes Sweat Rate & Sodium Loss via TotalSweatLoss_L = (PreWeight_kg − PostWeight_kg) + FluidDrank_L; SweatRate_L_hr = TotalSweatLoss_L / Duration_hrs.

Frequently Asked Questions

How does the Athlete Sweat Rate (L/hr), Dehydration % & Sodium Electrolyte Replacement Calculator compute its result?

It evaluates TotalSweatLoss_L = (PreWeight_kg − PostWeight_kg) + FluidDrank_L; SweatRate_L_hr = TotalSweatLoss_L / Duration_hrs directly in your browser and updates three custom SVG visualizations in real time.

Can I use Goal Seek to solve backwards for a target lab value or pace?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input parameter.

Are my health and biometric inputs kept private?

Yes. All calculations run 100% locally on your device with zero external transmission.

Health & Fitness · Sports Nutrition & Supplementation

Athlete Sweat Rate (L/hr), Dehydration % & Sodium Electrolyte Replacement Calculator: inputs, method, and how to read the result

Compute hourly sweat loss (L/hr), % body weight lost, and sodium mg/hr replacement.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Pre Exercise Weight Kg: Nude/minimal-clothing weight before exercise (kg).
  • Post Exercise Weight Kg: Weight immediately after exercise (toweled dry, kg).
  • Fluid Consumed During Ml: Total water/sports drink consumed during the session (mL).
  • Exercise Duration Minutes: Total exercise duration in minutes.

What the calculation includes

With the default values shown, Hourly Exercise Sweat Rate is 1.48 L/hr. The calculation follows Sweat Rate & Sodium Loss Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Pre Exercise Weight Kg from 73 kg to 80 kg changes Hourly Exercise Sweat Rate from 1.48 L/hr to 7.08 L/hr. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses peer-reviewed clinical and sports physiology formulas.
  • For educational and informational reference only; clinical scores do not replace physician judgment or laboratory reference ranges.

Scope: Global Clinical & Sports Science Consensus Check the assumptions and limitations against your situation before relying on the estimate.

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