Water Intake Calculator

Estimate your recommended daily water intake from your weight, activity level and climate. See your total daily target, an hourly average and extra water for exercise.

Choose your unit system, then enter your weight in kg (metric) or pounds (imperial). Pick your activity level and climate to fine-tune the estimate. The base is about 35 ml of water per kg of body weight, plus additions for activity and heat.

Daily water intake
Daily intake (ml)
Average per hour (16h awake)
Extra for exercise

A water intake calculator estimates how much water you should drink each day based on your body weight, how active you are and the climate — including the extra you need during and after exercise.

The maths

  • Base = weight (kg) × 0.035 (about 35 ml/kg)
  • + activity: sedentary 0 up to extra active 1.4 litres
  • + climate: 0 to 1 litre in hot/humid conditions

Food supplies about 20% of daily water; the rest comes from drinks.

Examples

  • 70 kg, moderate activity, temperate = ~3.15 litres/day
  • Add ~0.5–1 litre for every hour of intense exercise
  • Hot climates can push the total above 4 litres

Frequently asked questions

Do coffee and tea count?

Yes. Mild caffeinated drinks still contribute to hydration. Plain water is ideal, but milk, juice, tea and coffee all count towards your total (watch the calories and sugar).

Can I drink too much water?

Yes — drinking far beyond thirst can dilute blood sodium (hyponatremia). These figures are guides; drink to thirst and more in heat or during exercise.

Just for the giggles, much love.
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