This sweat rate calculator lets you enter your weight before and after exercise, how much fluids you ingested during exercise, and how much fluid you urinated during exercise, to come up with a sweat volume. You further need to enter how long you exercised to get the calculator to give you your sweat rate.
Related: In this article I give you step by step instructions on gathering your data to put into your sweat rate equation or the below calculator.
Sweat rate calculator using pounds of body weight and ounces of fluid intake and output
How does this calculator work?
This calculator is a modified version of the CDC and National Athletic Trainers’ Association sweat rate equation. I’ve just modified it to use pounds of body weight and US fluid ounces.
Original CDC or NATA sweat rate equation
[(pre-exercise weight in kg + fluid intake during exercise in L) – (post-exercise weight in kg + urine output during exercise in L)]/time spent exercising in hours
Modified sweat rate equation
[(pre-exercise weight in pounds * 15.34oz./pound + fluid intake during exercise in oz.) – (post-exercise weight in pounds * 15.34oz./pound + urine output during exercise in oz.)]/time spent exercising in hours
What is a normal sweat rate?
A normal sweat rate is between 0.5 and 2L per hour, for athletes of all body sizes, during their activities, with the median being 1.2L per hour. When taking into account the size of the athlete, via body weight, the normal sweat rate is between between 10 and 25mL/kg/h, with a median around 16mL/kg/h, or 1.12L/h for a 70kg person.
In terms of ounces, this works out to be 16.9 to 67.6 fluid ounces per hour, for again athletes of all body sizes, with the median at 40.6 fluid ounces per hour. Again normalizing this data for body size, the normal sweat rate is 0.338oz/kg/h to 0.845oz/kg/h, with the median being 0.541oz/kg/h. Considering body weight in pounds, this is 0.154oz/lb/h to 0.384oz/lb/h, with the median at 0.245oz/lb/hr.
Further Reading
Check out my article, How To Calculate Your Sweat Rate, for detailed instructions on the data gathering and interpreting your data with examples.
Check out my article, Sweat, Mineral and Micronutrient Losses When Hiking in the Heat, on your electrolyte and vitamin losses through sweat, and what you should do about it.
And also swing back to my main Hiking Nutrition page for info on everything sports nutrition related as it applies to hiking.