# Water Intake Calculator: How Much Water Should I Drink a Day?

How much water to drink a day: 3.7 litres for men and 2.7 litres for women (National Academies), about 80% from drinks, plus sweat lost in exercise.

Interactive tool: https://lookup.sg/tools/water-intake-calculator

## How this works
The daily target is the Adequate Intake of total water set by the US National Academies (Institute of Medicine) in its 2004 Dietary Reference Intakes: 3.7 litres a day for adult men and 2.7 litres for adult women, 3.0 litres in pregnancy and 3.8 litres while breastfeeding. Total water counts everything: plain water, other drinks including tea and coffee, and the water in food.

About 80% of total water comes from drinks and 20% from food, so the drinks figure is 80% of the target, shown in 250 ml glasses. The reference values are set for healthy people in temperate climates; the National Academies notes that people who are very active or live in hot climates may need more, and that very active people in constant heat often need 6 litres or more.

For exercise, weigh yourself before and after: each kilogram lost is roughly a litre of sweat that the target above does not include. Thirst is a reliable guide for most healthy people. People with kidney, heart or liver conditions, or on a fluid limit, should follow their doctor's advice instead.

## FAQs
### How much water should I drink a day in Singapore?
About 3 litres from drinks for men and about 2.2 litres for women, which is 80% of the National Academies' total water targets of 3.7 and 2.7 litres. In Singapore's heat, or when you exercise, you need more to replace sweat.

### Is 8 glasses of water a day enough?
Eight 250 ml glasses is 2 litres, a little under the 2.2 litres of drinks a typical woman needs and well under the 3 litres for a man. Food, tea, coffee and other drinks count towards the total too.

### How much water should I drink after exercise?
About 1 litre for every kilogram of body weight lost during the session, on top of your daily target. Weigh yourself before and after a run or game to see how much you sweated.

### Does coffee count towards water intake?
Yes. The National Academies' total water figures include all beverages, including caffeinated drinks, as well as the water in food.

## Sources
- [National Academies: Report sets dietary intake levels for water, salt and potassium (2004)](https://www.nationalacademies.org/news/report-sets-dietary-intake-levels-for-water-salt-and-potassium-to-maintain-health-and-reduce-chronic-disease-risk)
- [National Academies: Dietary Reference Intakes summary tables (total water by life stage)](https://www.ncbi.nlm.nih.gov/books/NBK56068/table/summarytables.t4/)

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