TopToolsAiEstimate how much water you should drink per day based on your body weight and activity level, shown both in litres and as an easy-to-track number of glasses. Someone weighing 70kg with a moderately active routine typically lands around 2.4 litres a day, or roughly ten 240ml glasses — the common one-size 8-glasses-a-day rule is a rough average that ignores body weight entirely.
Last updated: 1 Sep 2026
How to use Daily Water Intake Calculator
- Enter your weight in kilograms.
- Select your activity level.
- Click "Calculate" to see your recommended daily water intake in liters.
Frequently asked questions
Does climate affect how much I should drink?
Yes — hot or humid weather increases fluid loss through sweat, so you may need more than the base estimate on those days.
Does coffee or tea count toward this total?
Most fluids count, though very high caffeine intake can have a mild diuretic effect. Plain water is still the most reliable way to hit your target.
Does exercise increase how much water I need?
Yes, significantly — you lose extra fluid through sweat during exercise, so add more water on workout days beyond this baseline estimate.
Is there such a thing as drinking too much water?
Yes, in rare cases drinking excessive amounts in a short time can cause a dangerous condition called hyponatremia — moderation and spreading intake through the day matters.
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