Water Intake Calculator

How Water Needs Are Estimated

There is no single perfect number, but a widely used rule of thumb is 30–35 ml per kilogram of body weight per day for healthy adults in a temperate climate. This calculator uses 33 ml/kg as its baseline, then adds water for exercise and hot climates.

Why the Amount Varies

• Body size: larger bodies need more water.
• Exercise: you lose water through sweat — roughly 0.5–1 litre per hour of moderate exercise.
• Climate: hot and humid environments increase sweat losses.
• Diet: high-protein and high-fibre diets increase water needs.
• Pregnancy and breastfeeding: increase water needs (consult your doctor for personal guidance).

Other Sources of Water

About 20% of your daily water typically comes from food (fruit, vegetables, soups, yogurt). Coffee, tea, and other drinks also count toward hydration, though they may have mild diuretic effects. This calculator gives the target for drinks and water combined, not just plain water.

Signs of Good Hydration

• Urine is pale straw-coloured.
• You rarely feel thirsty.
• You can urinate 4–7 times per day.
• You have steady energy and no headaches.