Daily Water Intake
Recommended daily water intake by weight and activity (L/day).
How it works
Base intake ≈ weight(kg) × 33 ml, then +10%–50% by activity
Most adults need about 30–35 ml/kg per day; more with exercise, heat, or lactation. Food and other drinks also supply water.
FAQ
Do I need 8 glasses a day?
"8 glasses" is a rough rule of thumb; real needs depend on weight, activity and climate, so weight-based estimates are more personal.
Worked example
70 kg at 30–35 ml/kg: 70 × 35 = 2,450 ml, i.e. about 2.1–2.45 L per day.
Add 500–750 ml for an hour of moderate exercise, and more in heat or with heavy sweating.
Notes and limitations
Food — especially fruit, vegetables and soup — supplies about 20% of total water, so drinking can be below the total. People with heart, kidney or liver disease must follow medical advice rather than a general formula. Pale-yellow urine is a reasonable everyday check.