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Sweat Rate Calculator 

Do you want to optimize your athletic performance? One important aspect to consider is hydration. But with so many variables at play, figuring out the right amount of fluids to consume during exercise can be challenging!

That is where our sweat rate calculator comes in. By accurately measuring your sweat rate, you can determine how much fluid you need to consume per hour of exercise to maintain proper hydration levels.

In this article, we will walk you through the steps for collecting accurate information to use our sweat rate calculator and help you create a personalized hydration plan to help you perform at your best.

What is your sweat rate?

Sweat rate is an essential measurement used to determine how much fluid an athlete loses during exercise. 

The goal of calculating your sweat rate is to figure out how much water you should consume during exercise to prevent dehydration or overhydration! 

Calculating your sweat rate can help prevent dehydration, heat illness, electrolyte imbalance, and injury as well! 

Why does sweat rate matter?

A loss of 2% of body weight  (3 lbs in a 150lb athlete) is detrimental to physical performance. 

For example, a 150lb swimmer who is dehydrated will struggle to hold pace towards the end of a workout, they may cramp, and they may feel more mentally fatigued than their hydrated teammate! 

A loss of fluids more than 2% of body weight loss can negatively impact performance and cognition. (1)

At Eat Swim Win, we are dedicated to helping athletes do all they can to achieve peak performance! Calculating sweat rate is one of the first things we recommend athletes do to crush their hydration plan. 

What do you need to calculate your sweat rate?

To calculate an accurate sweat rate you need:

  • An accurate scale
  • Nude body weight before/after exercise
  • The recorded amount of fluids consumed during exercise 
  • Duration of workout

If an athlete urinates after checking the initial weight or during the exercise the result will be inaccurate. 

Try to urinate before checking your pre-exercise weight. 

Use our sweat rate calculator 

Sweat Rate Calculator

How to get the most accurate sweat rate results 

We recommend performing this test at least three times and then taking the average of all three results to get a clearer idea of your sweat rate. 

For example:

Test 1: 30 oz

Test 2: 31.5 oz

Test 3: 28 oz

Add up all three values: 30 + 31.5 + 28 = 89.5 oz

Divide that value by 3: 89.5/ 3 = 28.8 oz, round up to 30 oz

Your average sweat rate will be ~30 ounces per hour or ~900 ml. 

Creating a hydration plan 

Once you know your sweat rate it can be easier to calculate how much to drink and when!

If you are a swimmer with a 30 oz sweat loss per hour you can divide this by 4 to calculate how much you should drink every 15 minutes. 

For example: 30 oz or 900 ml / 4 = 7.5 oz or 225 ml.

For this reason, it’s helpful to have water bottles labeled down the side in ml or oz. 

Factors that affect sweat rate 

Keep in mind that sweat rate can vary depending on many factors including:

  • Exercise intensity
  • Exercise duration
  • Fitness level
  • Acclimation to exercise in the heat
  • Relative humidity 
  • Type of clothing worn 

Don’t forget about electrolytes 

Our sweat calculator is a great tool for calculating fluids you need to consume to prevent dehydration but it does not factor in the amount of electrolytes you need per hour. 

To learn more about calculating your electrolyte needs we recommend checking out our Ultimate Hydration Guide For Swimmers


Calculating your sweat rate is crucial in developing a personalized hydration plan that will help you perform at your best as an athlete. 

By using our sweat rate calculator, you can determine the right amount of fluids to consume during exercise to avoid the detrimental impacts of dehydration.

It is essential to follow the steps for collecting accurate information to get the most precise results. Repeat these steps at least 3 times to get a clearer idea of your sweat rate. 

Once you know your sweat rate, it can be easier to calculate how much to drink and when. 

At Eat Swim Win, we are committed to helping athletes achieve peak performance. We hope our sweat rate calculator and Ultimate Hydration Guide for Swimmers will be helpful tools for your athletic journey!

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