Hydration Calculator for Athletes

Your personalized daily water target for training days and competition, with sweat-rate calibration and electrolyte timing.

Calculate your target

Prefilled for this goal — adjust anything to match you.

Personal Details
Age Group
Activity Level

extreme - 90+ minutes of extreme physical activity.

RestingLightModerateIntenseExtreme
Health & Lifestyle Factors
Climate

Adjust for your local weather. We look up temperature, humidity, and elevation for your area — your health details never leave this page.

Athletic hydration is a two-layer problem: the daily baseline you recover between sessions on, and the session-specific replacement layered on top. This calculator nails the baseline using your weight, sex, and training volume; the session layer you calibrate yourself with pre/post weigh-ins. Sweat sodium concentration varies substantially between individuals — if you cramp in long events or see white streaks on dark clothing after workouts, you likely sweat salty and should prioritize electrolytes rather than plain water. On double-session days, rehydrate at roughly 150% of fluid lost to return to baseline before the next start.

Key points for this goal
  • Baseline from weight, sex, and training load — then layer session losses
  • Calibrate sweat rate: weigh before/after hard sessions (1 kg ≈ 1 L)
  • Salty sweaters: cramps + white residue mean prioritize electrolytes
  • Double-session days need 150% of losses replaced before restarting

Hydration Calculator for Athletes — FAQ

How much should athletes drink per hour of training?

Typical range is 400-800 ml per hour depending on sweat rate, heat, and intensity. Elite marathoners in cool conditions may need under 400 ml/h; big athletes doing two-a-days in heat can exceed a litre. Your own weigh-in data beats every rule of thumb.

Do I need electrolytes or is water enough?

Under about 90 minutes, water plus normal meals covers it. Beyond that, or in heat where you are sweating heavily, add sodium — through sports drink, tabs, or salty food. The saltier your sweat (cramping, white streaks on clothing), the more deliberate you should be.

Sources: American College of Sports Medicine Position Stand: Exercise and Fluid Replacement (Sawka MN et al., Medicine & Science in Sports & Exercise, 2007) · ACSM/AND/DC Joint Position Statement: Nutrition and Athletic Performance (Thomas DT, Erdman KA, Burke LM, Medicine & Science in Sports & Exercise, 2016) — see our methodology for how they map to the calculation.