💧 Sweat Rate Calculator
How much fluid you lose per hour of exercise
About this calculator
Weighing yourself before and after exercise is the simplest way to measure how much fluid you lose as sweat. This calculator turns that weight change, plus what you drank and lost, into an hourly sweat rate. Knowing your number takes the guesswork out of hydration for long runs, rides, and hot days.
Tip: Test on a typical training day, not race day. Sweat rate changes with heat, humidity, and intensity, so retest when the season changes.