Am I drinking enough? Hydration check

Add up the drinks you had today. The tool shows the total in litres, compares it with the reference level for drinks, and adds the caffeine and sugar in the same drinks.

How to use the hydration check

Choose a drink in each row and the number of glasses or cups. Use “Add another drink” for up to eight rows. We count 1 g of drink as 1 ml. Water is counted as a glass of 8 fluid ounces (about 237 ml).

What the reference levels mean

A 2004 report from the National Academies set a reference level of 3.7 litres of total water a day for adult men and 2.7 litres for adult women. “Total water” means all drinks and the moisture in food. About 80 percent comes from drinks, including caffeinated drinks, and about 20 percent from food. So the drinks share is roughly 3.0 litres for men and 2.2 litres for women (our calculation).

The numbers cover the expected needs of healthy, sedentary people in a temperate climate. The report gives no “8 glasses a day” rule: thirst and drinking with meals are enough for most people. Very active people exposed to hot weather often need six litres or more of total water. The report also says caffeinated drinks can contribute as much as non-caffeinated ones, and that drinking water in excessive amounts can be life-threatening.

Where the numbers come from

National Academies news release: Report Sets Dietary Intake Levels for Water, Salt, and Potassium (read 2 Nov 2026). Caffeine and sugar per drink: USDA FoodData Central, with the 400 mg caffeine figure from the FDA and the sugar limit from the WHO.

General information, not medical advice. If you have a kidney or heart condition or a fluid limit from your doctor, follow your doctor.