Daily Water Intake Calculator
Enter your weight and how long you exercise on a typical day to get a rough daily water target.
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Formula
litres = (weight in kg × 35 + exercise minutes ÷ 30 × 350) ÷ 1000
One glass is counted as 250 ml.
Worked example
70 kg and 60 minutes of exercise: 70 × 35 = 2,450 ml, plus 60 ÷ 30 × 350 = 700 ml, gives 3,150 ml. That is 3.15 litres, or 12.6 glasses of 250 ml.
Frequently asked questions
How much water should I drink a day?
A common rule of thumb is 35 ml per kg of body weight. At 70 kg that is 70 × 35 = 2,450 ml, or about 2.45 litres, before any exercise.
How does exercise change the amount?
This calculator adds 350 ml for every 30 minutes of exercise. 60 minutes adds 700 ml, so a 70 kg person needs about 3.15 litres in total.
Does food and other drinks count?
Yes. Tea, coffee, soup and water-rich foods such as fruit all contribute, so the figure is a total fluid target, not only plain water.
Is this a medical recommendation?
No. Heat, illness, pregnancy, and kidney or heart conditions change fluid needs. Ask a health professional if you have a medical condition.