How to work out your daily water intake
- Choose who it’s for under Who.
- Pick litres or US fluid ounces and cups.
- Read how much to drink a day, the total including water from food, and the European figure for adults.
Where the numbers come from
The figures are the adequate intakes for water in the Dietary Reference Intakes published by the US National Academies (then the Institute of Medicine) in 2004. They are set at the amount healthy people typically drink and eat, not a strict minimum.
| Group | Total water a day | From drinks |
|---|---|---|
| Women, 19 and over | 2.7 L | 2.2 L |
| Men, 19 and over | 3.7 L | 3.0 L |
| Pregnant | 3.0 L | 2.3 L |
| Breastfeeding | 3.8 L | 3.1 L |
| Girls, 14 to 18 | 2.3 L | 1.8 L |
| Boys, 14 to 18 | 3.3 L | 2.6 L |
| Girls, 9 to 13 | 2.1 L | 1.6 L |
| Boys, 9 to 13 | 2.4 L | 1.8 L |
| Children, 4 to 8 | 1.7 L | 1.2 L |
| Children, 1 to 3 | 1.3 L | 0.9 L |
The European Food Safety Authority set lower adequate intakes for adults in 2010: 2.0 litres a day of total water for women and 2.5 litres for men, rising to 2.3 litres in pregnancy and 2.7 litres when breastfeeding. The calculator shows that figure next to the US one for adults.
Needs vary
These are averages. A large, active person working outdoors in summer can need far more, and a small person in a cool office less. Drink to thirst, drink more around exercise and in the heat, and use the colour of your urine as a check: pale straw is about right.