How much water do I need?

A common baseline is 35 ml per kg of body weight. Athletes, hot climates, and illness need more. The old '8 glasses a day' is ~2L — adequate for sedentary people but too little for active ones.

Does coffee/tea count?

Yes — while caffeine is a mild diuretic, the water in coffee/tea still hydrates you. The diuretic effect is smaller than the water input.

Health

Water Intake Calculator

Compute your daily hydration target based on body weight, activity, and climate. Includes glass/cup conversions and hourly schedule.

Units

Weight

Activity

Climate

Illness / extra loss?

Hydration tips

Drink first thing: a glass of water on waking rehydrates after sleep
Before meals: a glass 30 min before eating aids digestion
Check urine color: pale yellow = good. Dark = drink more.
Don't overdo: excessive water (>6 L/day) can cause hyponatremia
Pre-workout: 500 ml 2 hours before exercise
Post-workout: 500 ml per 0.5 kg of sweat lost

Frequently asked questions

How much water?

Baseline 35 ml/kg. Athletes, hot climates need more.

Coffee/tea count?

Yes — water in coffee still hydrates despite mild diuretic.