Sweat Rate Equation

Ever wanted to know exactly how much you should be drinking to replace fluid losses during exercise? If not, you should. You could be slightly dehydrated and not even know it!

*Information taken from the Sports Nutrition Care Manual published by the Academy of Nutrition and Dietetics.

Ensure that the athlete is well hydrated before exercise. Instruct the athlete to warm up for 5 to 10 minutes until he or she breaks into a sweat. Advise the athlete to urinate if needed. Then, follow these instructions.

  1. Record nude body weight before exercise in kg (lb/2.2 = kg)
  2. Record nude body weight after exercise in kg (lb/2.2 = kg)
  3. Record change in body weight in g (A – B x1,000 grams)
  4. Record drink volume consumed during exercise in mL (oz x 30 = mL)
  5. Record urine volume excreted before postexercise weighing in mL (oz x 30 = mL)
  6. Determine sweat loss (C (g) + D (mL) – E (mL), oz x 30 = mL)
  7. Record exercise time, minutes or hours
  8. Calculate sweat rate = F/G in mL/min or mL/hr

(Murray 1996; Sawka 2007)