Hydration · Racing
Sweat Rate Calculator: Your Hourly Hydration Target
Weigh yourself before and after a training session, log the fluid you drank during it, and get your sweat rate in liters per hour, the most useful single number for building a race-day hydration strategy.
Enter your pre and post weight to see your sweat rate.
How the sweat rate calculator works
Sweat rate is the simplest way to know how much fluid you actually lose per hour during exercise. Every other hydration metric, such as thirst, urine color, or body water percentage, is less reliable. A 60-minute test in conditions close to race day gives you a number you can actually use.
The protocol: weigh yourself naked (or in dry shorts) just before the session. Train for a measured duration (60 to 90 minutes works best). During the session, track every ounce or milliliter of fluid you consume. Immediately after, towel off, strip down, and weigh yourself again.
The math: sweat loss in liters = (pre-weight − post-weight) + fluid consumed. Assume 1 kg = 1 L of water. Divide by hours to get sweat rate per hour.
Most endurance athletes sweat 0.5 to 1.2 L/hr in cool conditions and 1.0 to 2.5 L/hr in the heat. Your target during a race is usually 70 to 100 percent of your sweat rate. You rarely need to replace every drop, but you want to avoid losing more than 2 percent of body weight in the process.
Sweat loss (L) = (pre-weight − post-weight) + fluid consumed · Sweat rate (L/hr) = sweat loss ÷ duration
Frequently asked questions
Should I fully replace my sweat rate during a race?
How often should I retest my sweat rate?
Do I need electrolyte drink or plain water?
Why did I gain weight during a workout?
CoreRise / Endurance training
Cora builds your hydration plan
Enter your sweat rate once and CoreRise applies it to every session and every race brief: how much to drink per hour, how much sodium to carry, and how to adjust for heat. Cora also checks your post-workout weight trend and flags you if you are drifting toward chronic dehydration.
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