HYDRATION · SWEAT
Sweat Rate Calculator
Calculate your personal sweat rate from pre/post-exercise weigh-ins and estimate fluid and sodium losses using ACSM guidelines.
Try a preset
Result
Hydration metrics
Sweat rate, total fluid lost, and recommended hourly replacement.
Hydration status
Mild Dehydration
You lost 1.1% body weight. Mild dehydration can slightly reduce performance. Increase fluid intake by ~1050 mL/hr next session.
How to use it
- Open Sweat Rate Calculator and enter your current baseline accurately.
- Adjust one variable at a time so changes are easy to interpret.
- Review the headline output first, then inspect supporting metrics.
- Run at least one conservative and one aggressive scenario.
- Use outputs to set your next training or nutrition action for the week.
- Save or share this setup if you want to revisit it later, then check one easier and one harder version before you change your plan.
Questions people usually ask
What is sweat rate?
Sweat rate is the volume of fluid lost through sweating per hour of exercise, measured in litres/hour. Average endurance athletes sweat 0.5–2.5 L/hr; heavy sweaters can exceed 3 L/hr in heat.
Which formula is used?
The ACSM (American College of Sports Medicine) standard formula: Sweat Rate (L/hr) = (Pre-weight − Post-weight + Fluid consumed − Urine produced) / Duration in hours. Each 1 kg body weight loss equals approximately 1 litre of sweat.
How do I weigh myself accurately?
Weigh yourself nude immediately before exercise, then nude again immediately after — before eating or drinking anything post-exercise. Use the same scale both times.
Do I need to track urine output?
For most workouts under 90 minutes, urine output is negligible and you can leave it at 0. For ultra-endurance events, tracking urine output improves accuracy.
Why does sodium loss matter?
Sweat contains sodium (average ~920 mg/L). High sweat rates deplete sodium faster, risking hyponatremia in long events. If you lose more than 800 mg/hr, consider electrolyte drinks or salt tabs.
Is this tool free and private?
Yes. AI Fit Hub tools are free, browser-based, and no-signup. Your inputs stay in your browser.
Does this replace a sports dietitian?
No. These outputs are evidence-based estimates. For personalised hydration plans, especially for elite performance or medical conditions, consult a registered sports dietitian.
Related Resources
Learn the decision before you act
Every link here is tied directly to Sweat Rate Calculator. Use the explanation, formula, examples, and benchmarks to pressure-test the calculator output from first principles.
How To Use
5 STEPSHow to Use Heart Rate Zone Calculator
Optimize your workouts by learning how to use the Heart Rate Zone Calculator. Personalize training intensity for weight loss, endurance, or general fitness goals.
ReadHow To Use
5 STEPSHow to Use Sleep Calculator
Optimize your sleep and wake up refreshed! Learn how to use the AI Fit Hub Sleep Calculator to find ideal bedtimes and wake-up times based on sleep cycles.
ReadHow To Use
5 STEPSHow to Use Sweat Rate Calculator
Optimize your hydration strategy. This guide shows how to use the AI Fit Hub Sweat Rate Calculator to understand your fluid loss during exercise and prevent dehydration.
ReadGuide
6 MIN READHow to Stay Hydrated During Exercise
Optimize your performance and prevent dehydration during workouts with expert strategies, personalized fluid intake guidelines, and essential electrolyte balance tips.
ReadFormula
6 VARIABLESSweat Rate Formula
Calculate your individual sweat rate using this comprehensive formula from AI Fit Hub. Understand fluid loss during exercise to optimize hydration and performance in any sport.
ReadFormula
4 VARIABLESWater Intake Formula
Optimize your daily water intake with our comprehensive formula. Learn how to calculate your personalized hydration target based on body weight, activity, and climate for peak health.
ReadContinue With Related Tools
Estimate your total daily energy expenditure using the Mifflin-St Jeor equation and activity multipliers.
Open →Convert your calorie target into daily protein, carbs, and fat grams based on your goal and split preference.
Open →Estimate required calorie deficit and timeline pacing for a bodyweight change target.
Open →Plan a realistic body-recomp timeline with body-fat targets, training frequency, calorie pacing, and protein guidance.
Open →