Water Intake Calculator — How Much Water Should You Drink Per Day?
Calculate your personalised daily water intake from weight, activity level, and climate. Get targets in litres, ml, and glasses per day. Evidence-based formula.
Daily Target
3.1L
3150 ml
Glasses (250ml)
13
glasses of water
Base (35ml/kg)
2.5L
without exercise
Formula: 35ml × body weight + exercise + climate adjustments. Use thirst as your primary guide.
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Frequently Asked Questions
Quick answers to common questions
How much water should you drink per day?+
The National Academy of Medicine recommends 3.7 litres for men and 2.7 litres for women from all sources. Practical formula: 35ml per kg of body weight. Add 500ml for every 30 minutes of vigorous exercise.
Can you drink too much water?+
Yes. Overhydration (hyponatremia) dilutes blood sodium. Risk is real for endurance athletes drinking large volumes without electrolytes. Use thirst as your primary guide and pale yellow urine as a secondary indicator.
Does coffee count toward daily water intake?+
Yes. Despite caffeine's mild diuretic effect, caffeinated beverages contribute net fluid to hydration. The British Dietetic Association confirms tea, coffee, juice, and milk all count. Alcohol is the exception.