Water Intake Calculator

A common guideline is 30–35 mL of water per kilogram of body weight. This water intake calculator uses 33 mL/kg — the middle of that range — so a 70 kg adult gets about 2.3 liters (roughly 9–10 cups) before activity. Needs vary with climate, health and pregnancy, so treat the number as a starting point, not a strict rule.

Yes, mostly. Coffee, tea, milk, juice and watery foods like soup, fruit and vegetables all add to your daily fluids. Caffeine has only a mild diuretic effect at normal amounts, so a regular cup of coffee still hydrates you on balance. This calculator already assumes about 20% of your water comes from food, so it targets what you actually drink.

It can. Drinking very large volumes in a short time can dilute blood sodium and cause hyponatremia, which is dangerous. As a rule of thumb, avoid drinking more than about 1 liter in a single hour and spread your intake across the day. If your target here is very high, it reflects a large body weight or heavy activity — consult a professional before pushing far beyond it.

This water intake calculator adds a fixed activity allowance on top of the base amount: +0 mL for a mostly sedentary day, +350 mL for light-to-moderate exercise (1–3 times a week) and +700 mL for hard training or physical work (4+ times a week). On intense or hot days you may need more to replace sweat, so drink to thirst and check that your urine stays pale.

No. This water intake calculator runs entirely in your browser — your weight and activity level are never uploaded to any server. Your last entry is saved only in your browser's localStorage so the form is ready next time, and you can clear it anytime.