Calculate how much water you should drink per day based on your weight, activity level, and climate. See results in liters, oz, and number of glasses.
Added May 26, 2026
Input
Result
Enter a value for body weight to see your result.
Calculate your personalised daily water intake recommendation based on body weight, activity level, and climate. Results are shown in liters, ml, fluid ounces, and number of glasses or bottles.
A 70 kg person doing moderate exercise needs about 2.8 L (roughly 12 glasses) per day — more than the generic '8 glasses' advice, which assumes sedentary adults.
Inputs
Result
General guidance: 30–35 ml per kg of body weight per day as a baseline, adjusted for activity and climate. A 70 kg moderately active adult needs roughly 2.5–3.0 L total fluids per day. The old '8 glasses (2 L)' rule is a rough minimum for sedentary adults.
Yes. Despite mild diuretic effects, caffeinated drinks still contribute net fluid to your daily intake. Studies show that moderate coffee and tea consumption (up to 4–5 cups/day) does not cause dehydration in regular drinkers.
The simplest check is urine color. Pale yellow (like diluted lemonade) indicates good hydration. Dark yellow or amber means you need more water. Clear urine can mean you're overhydrating, which is also something to avoid.
Yes. Larger bodies have more cells and a higher metabolic rate, requiring more fluid. The per-kg formula (30–35 ml/kg) accounts for this. An 100 kg person needs significantly more water than a 60 kg person even at the same activity level.