How it is calculated
- Base: about 35 ml per kilogram of body weight per day for adults.
- Exercise: add about 500 ml per hour of physical activity.
- Hot climate: add 10–20%.
- Pregnancy: add about 300 ml; breastfeeding about 700 ml.
This covers all fluids; around 20% usually comes from food.
Worked example
70 kg, exercising an hour a day in a mild climate: 70 × 35 = 2,450 ml + 500 = about 2.95 litres, roughly 12 glasses.
Frequently asked questions
Do tea and coffee count?
Yes, they count as fluids; their diuretic effect is mild for regular drinkers.
How do I know I drink enough?
Pale yellow urine is a good sign; dark urine means you need more.
Can I drink too much?
Yes, extreme overdrinking is rarely dangerous. People with heart or kidney disease should follow medical advice.