How much should you drink during a workout?

A rule of thumb is about 0.4–0.8 liters per hour depending on the intensity of the workout and the temperature. Drink small amounts (2 dl) regularly rather than a large amount at once.

When do I need a sports drink?

In workouts lasting over an hour or in hard sessions, electrolytes and carbohydrates (a sports drink) help. Water is enough for shorter ones. Salt replaces the sodium lost through sweat.

How do I know my sweat rate?

Weigh yourself before and after a workout. The weight loss in kilograms roughly equals the fluid lost in liters. This helps you estimate your individual need.

What does dehydration cause?

Even a 2% loss of body weight as fluid impairs performance. Symptoms include fatigue, headache, cramps and difficulty concentrating. Severe dehydration is dangerous.

Sports Hydration Calculator

Name: Sports Hydration Calculator
Author: Miikka

Calculate how much fluid you lose and need during exercise by sweat rate. Prevent dehydration. Free hydration calculator.

By Miikka · CalcBrew · Updated Sep 16, 2026

Workout duration: 60 min

Sweat rate: Moderate

Temperature: Normal

27.1 fl oz

Fluid to drink during workout

Fluid loss (sweat)	27.1 fl oz
Drink during workout	27.1 fl oz
Drink in 200 ml portions	3 times
Over 60 min: add electrolytes	0 (1 = yes)

ℹ️ Sweat rates vary from person to person. Drink about 200 ml every 15–20 minutes. Add salt/electrolytes for workouts over an hour. Weigh yourself before and after — 1 kg of weight lost = 1 liter of fluid.

This sports hydration calculator estimates how much fluid you lose through sweat and how much you should drink during a workout. That way you avoid dehydration and keep your performance up throughout the session.

How the calculator works and what it’s for▾

How fluid needs are calculated

The calculator estimates fluid loss from workout duration, how heavily you sweat and the temperature. The longer and harder the session in heat, the more fluid evaporates as sweat.

The recommendation is to drink about two decilitres every 15–20 minutes, keeping hydration steady so thirst does not catch you off guard mid-session.

What you enter and what you get

Enter the workout duration in minutes, estimate your sweat level and select the temperature.

You get the estimated fluid loss, the recommended amount to drink during the workout, how many two-decilitre servings that is, and a reminder to add electrolytes if the session runs over an hour.

Who it is for and when

The tool suits runners, cyclists, team-sport players and gym-goers who want to time their drinking correctly during long or hot sessions.

It is especially useful for endurance efforts and in the heat, when the risk of dehydration rises quickly.

Tips

For sessions over an hour, add salt or electrolytes, since plain water does not replace the salts lost in sweat.

Sweat rate is individual. You can check your real loss by weighing yourself before and after a workout: a one-kilogram drop equals roughly one litre of fluid.

🔄 Reviewed June 2026

Frequently asked questions

Cite this calculator

APACalcBrew. (2026). Sports Hydration Calculator. https://calcbrew.com/sports-hydration-calculator

MLA“Sports Hydration Calculator.” CalcBrew, 2026, calcbrew.com/sports-hydration-calculator.

Link to https://calcbrew.com/sports-hydration-calculator. Results are estimates; cite the underlying formula or data source for academic work.

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