Daily Water Intake Calculator

How much water should I drink daily calculator by weight — get your personal hydration target. Use the free Daily Water Intake Calculator below — enter your values and get instant results, right in your browser. Daily water (liters) = body weight (kg) × 0.035 × day factor (1.0 normal, 1.25 hot/exercise). Glasses = liters ÷ 0.25. A 65 kg adult on a normal day needs about 2.28 liters.

How to use the Daily Water Intake Calculator

"Drink 8 glasses a day" ignores the obvious: a 50 kg person and a 90 kg person need very different amounts of water. This how much water should I drink daily calculator by weight personalizes the target to your body weight — about 35 ml per kilogram — and adjusts for hot weather or exercise days. Enter your weight, get your liters and glass count, and hydrate with confidence.

  1. Enter your body weight in kilograms in the Body weight field.
  2. Choose Normal day, or Hot weather / exercise day if it applies.
  3. Click the Calculate button.
  4. Read your daily target in liters and in 250 ml glasses.
  5. Spread the glasses through the day rather than drinking all at once.

Formula

Daily water (liters) = body weight (kg) × 0.035 × day factor (1.0 normal, 1.25 hot/exercise). Glasses = liters ÷ 0.25. A 65 kg adult on a normal day needs about 2.28 liters.

Worked example

Weight 65 kg, normal day. Click Calculate. Target = 65 × 0.035 = 2.28 liters, about 9 glasses of 250 ml. On a hot exercise day the same person needs 2.84 liters — roughly 11 glasses. Spread intake through the day, and remember that food itself supplies about a quarter of your water.

Frequently asked questions

Mostly yes — they still hydrate you, though plain water is best. Very sugary drinks are not ideal substitutes.

Yes, extreme overdrinking can dilute blood sodium. Stick near your target and drink to thirst on top of it.

Yes. Choose the hot weather option, which adds 25% to cover extra sweat loss in Pakistani summers.

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