Nutrition & supplements
How much water should you drink per day?
Recommended liters of water per day based on weight and physical activity.
Quick answer
A practical estimate: 35 ml per kg of body weight, plus about 350 ml per 30 minutes of exercise. At 75 kg with no sport: 75 × 35 = 2,625 ml ≈ 2.6 litres. Add 60 minutes of training and the total rises to about 3.3 litres.
Recommended water per day
2.6 liters
- Base need (35 ml/kg)
- 2.6 liters
- Glasses (250 ml / 8 oz)
- 11
Estimate of 35 ml per kg plus roughly 350 ml per 30 minutes of sport. Hot weather and breastfeeding increase the need. Part of your fluids also comes from food.
How it works
The old "8 glasses" rule ignores body size and sweat loss. Urine colour is a simple check: pale yellow is fine; dark amber means drink more. Food (fruit, soup, vegetables) contributes roughly 20% of daily fluid intake. A time-marked water bottle on your desk makes the target visible without an app.
Long workouts and hot days may need electrolyte powder beyond plain water — especially sessions over 90 minutes. Kidney disease, heart failure or fluid-restricted diets: follow your clinician’s fluid prescription, not generic ml/kg rules. Hydration guidance only, not medical advice.
Two corrections to the usual advice. Coffee and tea count towards the total — the diuretic effect of a normal daily intake is far smaller than the water in the cup, so the idea that a coffee needs a glass of water to cancel it is simply not the case. And on the other side, more is not always safer: during efforts lasting several hours, drinking large volumes of plain water while sweating dilutes blood sodium, and the early symptoms — headache, nausea, confusion — read exactly like dehydration, so the instinct is to drink more. Beyond about ninety minutes of sweating, the fluid should carry salt.
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Frequently asked questions
Can you drink too much water?+
Yes — hyponatremia (dangerously low sodium) can occur from excessive intake, especially during long endurance events. For most people, thirst and the 35 ml/kg guideline keep intake in a safe range. Spread intake through the day rather than chugging litres in one sitting.
Does coffee dehydrate you?+
Mildly at very high doses, but habitual coffee drinkers develop tolerance. A few cups count toward fluid intake net of the small diuretic effect. Alcohol, by contrast, is a net dehydrator — each alcoholic drink needs roughly one extra glass of water to offset.
How much more water in hot weather?+
Add 500 ml–1 litre on hot or humid days, more if you sweat heavily outdoors. There is no single formula — weigh yourself before and after exercise: each kg lost is roughly 1 litre of fluid to replace. Dark urine after a hot run is your body asking for electrolytes, not just water.
Do breastfeeding women need more water?+
Yes — lactation increases needs by about 700 ml/day above pre-pregnancy intake. Use body weight × 35 ml as a floor, then add for nursing and activity. Drink to thirst; forcing litres beyond comfort does not boost milk supply and can worsen nausea.
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