Water Intake Calculator

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Estimate how much water to drink each day from your body weight, exercise and climate. See the result in liters, ounces, cups and glasses. Free and instant.

kg
min
Daily water – liters
In ounces –
In cups –
Glasses –
Based on roughly 35 ml per kg of body weight, plus about 12 oz (355 ml) per 30 minutes of exercise, with a 10% bump for hot weather. A general guide, not medical advice.

About Water Intake Calculator

The water intake calculator estimates how much water to drink each day based on your body weight, how long you exercise and your climate. Results appear in liters, ounces, cups and eight-ounce glasses, in metric or imperial units.

The estimate starts from roughly 35 ml of water per kilogram of body weight, adds about 12 oz (355 ml) for every 30 minutes of daily exercise, and applies a 10% increase for hot climates where you lose more fluid to sweat.

It is a practical daily-hydration baseline for setting a water-bottle goal or a reminder app target. The figure is a general guide, not medical advice — individual needs vary with health conditions, diet and activity.

How to use Water Intake Calculator

  1. Choose metric or imperial units.
  2. Enter your body weight in kilograms or pounds.
  3. Set your daily exercise time in minutes.
  4. Pick your climate — temperate or hot.
  5. Read your daily water target in liters, ounces, cups and glasses.

Frequently asked questions

From about 35 ml per kilogram of body weight, plus roughly 12 oz (355 ml) per 30 minutes of exercise, with a 10% bump in hot climates. A 70 kg person with no exercise lands near 2.5 liters.

It is a rough one-size-fits-all figure. Weight-based estimates like this one scale with your body and activity, so a small sedentary person and a large active one get appropriately different targets.

Fluids from beverages and water-rich foods do contribute to hydration in practice. The calculator's target is total water intake, so you do not need to drink the whole figure as plain water.

You lose fluid through sweat and faster breathing during activity. The tool adds about 355 ml per half hour of exercise to replace those losses — more may be needed for intense sessions in the heat.

Treat it as an estimate, not medical advice. Kidney or heart conditions, pregnancy, medications and unusual climates all change fluid needs — ask a healthcare provider for personal guidance.
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