Calculateur d'Hydratation

Overview

The familiar '8 glasses a day' rule has no scientific basis. Actual water needs vary widely with body size, activity level, climate, diet, and individual physiology. The Institute of Medicine guidelines suggest about 3.7 liters total fluid for men and 2.7 liters for women — but this includes water from food (typically 20% of intake) and other beverages. Climate matters: a 30°C humid day can double your needs vs a cool office. Exercise adds 0.5–1 L per hour of activity.

How It Works

This calculator estimates daily fluid needs based on body weight (around 30–35 mL per kg body weight as a baseline), activity level (add 0.5–1 L per hour of exercise), and climate adjustments. Output is total fluid intake — about 70–80% should come from drinking water; the rest from food and other beverages. Coffee and tea count (despite caffeine, the net hydration effect is positive). Alcohol does not count and actually increases water needs.

When to Use This

Use this when starting a new fitness program, moving to a hot climate, recovering from illness, planning a long hike or sport event, during pregnancy or breastfeeding, or anytime your urine is consistently dark yellow (a sign of dehydration). Athletes use it to plan pre-, during-, and post-workout hydration. Office workers underestimate needs because air-conditioned environments accelerate insensible water loss.

Frequently Asked Questions