Health

Water Intake Calculator

Free daily water intake calculator — find out how many liters, ounces, and glasses of water you should drink per day based on your weight, activity level, and climate.

Water Intake Calculator is a free online health tool from FastDailyTools (How much water should you drink per day?). Free daily water intake calculator — find out how many liters, ounces, and glasses of water you should drink per day based on your weight, activity level, and climate. It runs entirely in your browser — no sign-up, no account, no email and no upload — and every result can be exported as a dated PDF report.

  • ✔ Price: free, unlimited use, no rate limits
  • ✔ Sign-up: not required
  • ✔ Privacy: all math runs client-side, nothing is uploaded
  • ✔ Export: one-click PDF report (2026 rates)
Liters / day
2.31 L
Ounces / day
78 oz
Glasses (250 ml)
9.2

Add extra water during intense workouts, illness, pregnancy, or breastfeeding.

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How to use Water Intake Calculator

  1. Enter your weight (kg or lb).
  2. Select your activity level.
  3. Choose your climate.
  4. See recommended daily water intake in liters, ounces, and glasses.

Frequently asked questions

How much water should I drink per day?

A common rule is 30–35 ml per kg of body weight — around 2.5 L for a 75 kg adult. Add more for exercise and hot weather.

Is 8 glasses a day right for everyone?

It is a rough guideline. Actual needs depend on weight, activity, climate, and diet. This calculator personalizes it.

Does coffee and tea count toward water intake?

Yes — despite mild diuretic effect, most fluids count. Plain water is still the best choice.

Can you drink too much water?

Yes — hyponatremia (water intoxication) is rare but possible above 4–5 L/day without electrolytes. Stick to your calculated target.

How much water for weight loss?

Drinking 500 ml 30 minutes before meals can reduce appetite. Stay at or slightly above your calculated intake.

In-depth guides for this calculator

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