Slobiq Health / Nutrition / Water intake calculator
Water intake calculator
Enter your weight, how long you exercise and the climate to see a daily range for drinks.
These are general estimates, not medical advice, and they do not replace a doctor, dietitian or trainer. If you are pregnant, under 18, have a health condition or take medication, talk to a professional before changing your diet or training.
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About this tool: Water intake calculator
Your body needs water for temperature control, digestion and circulation. Needs rise when you sweat. This calculator uses about 30 to 35 ml per kilogram as the base, adds roughly 0.5 to 0.75 litre for each hour of exercise and half a litre in hot weather.
About 20% of the water you take in normally comes from food, so the drinks column is 80% of the total. For comparison it shows the European Food Safety Authority reference intake: 2.0 litres a day for women and 2.5 litres for men, from all sources.
Formula
Total = 30 to 35 ml × weight + exercise hours × 500 to 750 ml + 500 ml in hot weather. Drinks = 80% of the total. Glasses = drinks ÷ 250.
Worked example
A 70 kg woman exercising 60 minutes in a temperate climate needs about 2,600 to 3,200 ml of water in total, of which about 2,080 to 2,560 ml from drinks, roughly 9 glasses.
Sources and accuracy
- Formulas and sources last reviewed
- Accuracy
- An estimate from published formulas. Real needs differ between people, so treat it as a starting point and adjust to how your body responds.
Frequently asked questions
Does coffee or tea count?
Yes, they contribute to your fluid intake. Water is still the simplest choice, and sugary drinks add calories.
How do I know if I drink enough?
Pale yellow urine and rarely feeling thirsty are good signs. Drink more when it is hot, during illness with fever and around exercise.
Can I drink too much?
Yes, very large amounts in a short time can be dangerous. Sip regularly rather than forcing large volumes, and ask a doctor if you have heart or kidney disease.