Water Intake Calculator for Exercise — Hydration Guide 2026

Exercise significantly increases water requirements. You lose 0.5–2 liters of sweat per hour depending on intensity and conditions. Dehydration of even 2% body weight reduces athletic performance by 10–20%. The general exercise hydration guideline: drink 500ml (17 oz) 2 hours before exercise, 250ml (8 oz) every 15–20 minutes during exercise, and 1.5× the weight lost in sweat afterward. Our exercise hydration calculator gives personalized targets based on your weight and workout duration. No sign-up required — your data never leaves your browser. Works instantly on desktop, tablet, and mobile. Completely free with no daily usage limits, no watermarks, and no account needed. Trusted by students, professionals, and businesses worldwide. FixFlowHub is a browser-based toolbox with 120+ free utilities covering PDF, image, text, calculator, and productivity tools.

Frequently Asked Questions

How much water should I drink before a workout?

Drink 500ml (17 oz) of water 2 hours before exercise and another 250ml (8 oz) 20–30 minutes before starting. This pre-loads your hydration.

How much water during a workout?

Drink 150–250ml (5–8 oz) every 15–20 minutes during exercise. For workouts over 60 minutes, consider an electrolyte drink to replace sodium lost in sweat.

Should I drink electrolytes or plain water for workouts?

For workouts under 60 minutes, plain water is sufficient. For longer sessions, especially in heat, electrolyte drinks or adding a pinch of salt to water helps prevent hyponatremia.

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