The common rule of thumb is about 35 ml of water per kg of body weight per day, plus roughly 350 ml for every 30 minutes of exercise. Example: a 70 kg person who doesn't work out needs about 70 × 35 = 2,450 ml — roughly 2.5 liters a day, or about 10 cups of 240 ml.
How is it calculated?
The calculation has two steps: first multiply your body weight in kilograms by 35 ml — that's your daily baseline. Then add about 350 ml for every 30 minutes of physical activity that day. The result is usually translated into 240 ml cups to make it easier to track. Keep in mind that about 20% of your fluids come from food — fruit, vegetables and soups — so you don't need to drink the entire amount as plain water.
Example: a 70 kg person with no workout needs 70 × 35 = 2,450 ml, about 2.5 liters or 10 cups; add an hour-long workout and you add roughly 700 ml more. This is a rule of thumb only: in Israel's summer heat, and during pregnancy or breastfeeding, needs are higher — and anyone with kidney or heart disease should follow personal medical guidance rather than the calculator.
Frequently asked questions
How many cups of water should I drink a day?
By the 35 ml per kg rule, a 70 kg person needs about 2.5 liters a day — roughly 10 cups of 240 ml. If you weigh more, exercise, or spend time in the heat, you need more, and part of the total comes from food anyway.
How do I know if I'm drinking enough water?
The simplest practical indicator is urine color: pale yellow means you're drinking enough, dark yellow means you should drink more. Thirst is a relatively late signal — in hot Israeli weather it's better to drink steadily through the day rather than wait until you feel thirsty.
Should I drink more in summer and during exercise?
Yes. In the heat and humidity of the Israeli summer the body loses more fluid through sweat, so needs rise above the baseline. During exercise, add about 350 ml for every 30 minutes of training. Kidney or heart patients should set their fluid intake with their doctor.
The information on this site is a general estimate for informational purposes only, is not medical advice and is no substitute for consulting a doctor. Your data is never stored.
