Estimated Post Exercise Fluid Requirements Calculator

Calculator created by Jeff Burmann, NSCA-CPT. Questions? Email Jeff


  1. Hydrate: Appropriately hydrate four hours prior to exercise, or as much as you can if you’re training in the early morning. See our Pre Exercise Fluid Requirements Calculator to find out what you need before your workout for optimal performance.
  2. Weigh-in: While well hydrated, weigh yourself just prior to your exercise bout. Record this number, you’ll need it later. If your not well hydrated, your performance will suffer.
  3. Workout and try to stay hydrated: Try to stay hydrated through your workout. Inevitably you’ll lose some fluids, so taking a systematic approach to hydrating will be crucial to avoid heat and hydration related injuries including death.  If possible, take a brief water break every 15 minutes or so, even if you don’t think you need to.
  4. Weigh-in again and re-hydrate: After exercise, weigh yourself again and do a bit of simple math to find out how much weight you’ve lost during your exercise session. All weight lost is fluid loss and should be replaced with water, sports drinks, or other electrolyte containing beverages. Generally, water is fine for re-hydration if your exercise bout is about 30-60 minutes in duration. If your exercising at increased intensity for longer than an hour, consider a sports drink to prevent electrolyte imbalances that may lead to hyponatremia (low sodium levels in the blood).


This calculator will take the guess work out of re-hydrating after exercise.


Sawka, M.N., L.M. Burke, E.R. Eichner, R.J. Maughan, S.J. Montain, and N.S. Stachenfeld. 2007. Exercise and fluid replacement position stand. Medicine and Science in Sports and Exercise.

Shirreffs, S.M., A.J. Taylor, J.B. Leiper, and R.J. Maughan. Sodium intake and post-exercise rehydration in man

National Strength and Conditioning Association’s “NSCA’s Essentials of Personal Training Vol. 2.” Human Kinetics. 2012