Water Intake Calculator
A daily drinking-water estimate from your body weight and exercise time.
- Baseline (35 ml per kg)2.45
- For exercise (350 ml per 30 min)0.35
- Daily water intake (litres)2.8
Inputs used
- Weight70 kg
- Exercise per day30 min
About this calculator
A common guideline puts baseline fluid needs around 35 ml per kilogram of body weight per day — about 2.5 litres for a 70 kg adult — plus roughly 350 ml for every 30 minutes of exercise to replace sweat losses.
Needs vary widely with climate, diet and health: hot weather, altitude, pregnancy and illness all raise them, and food (especially fruit and vegetables) typically supplies around 20% of total fluid. Thirst and pale-yellow urine remain the most reliable everyday indicators.
This is a general wellness estimate, not medical guidance — kidney, heart and some other conditions change safe fluid ranges, so follow professional advice where it applies.
Quick reference
Daily water intake by weight and exercise
Estimated litres per day: 35 ml per kg of body weight plus 350 ml per 30 minutes of exercise. Metric values.
| Weight | 0 min | 30 min | 60 min | 90 min |
|---|---|---|---|---|
| 50 kg | 1.8 | 2.1 | 2.5 | 2.8 |
| 60 kg | 2.1 | 2.5 | 2.8 | 3.2 |
| 70 kg | 2.5 | 2.8 | 3.2 | 3.5 |
| 80 kg | 2.8 | 3.2 | 3.5 | 3.8 |
| 90 kg | 3.2 | 3.5 | 3.8 | 4.2 |
| 100 kg | 3.5 | 3.9 | 4.2 | 4.6 |
| 110 kg | 3.9 | 4.2 | 4.6 | 4.9 |
Frequently asked questions
How much water should I drink a day?
A common guideline is about 35 ml per kilogram of body weight, so a 70 kg adult lands near 2.5 litres before exercise, rising to roughly 2.8 litres after a 30-minute workout. Climate, diet, pregnancy and illness all move the figure, so treat it as a starting point rather than a fixed rule.
Does food and other drink count toward my intake?
Yes — food typically supplies around 20% of total fluid, more if you eat plenty of fruit and vegetables, and tea, coffee and milk all count despite the mild diuretic effect of caffeine. The litres shown here are a total target, not water you must drink on top of everything else.
Can you drink too much water?
It is possible but uncommon: drinking far more than the kidneys can clear can dilute blood sodium, a condition called hyponatremia. For most healthy adults thirst and pale-yellow urine are reliable everyday guides, but some heart and kidney conditions require a specific fluid limit set by a doctor.
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Results are informational only — not financial, medical or legal advice.