Water intake calculator

How much to drink a day, by the reference values of EFSA and the US National Academies, in liters, ounces and glasses. Then a reminder that spreads the glasses over your day.

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Rings while this tab is open and the computer is awake.

Reminder App for Chrome: reminders that ring with no tab open

This page rings only while it stays open. Our free Chrome extension keeps your reminders in Chrome’s side panel and rings each one with a notification and a sound whenever Chrome is running, on every computer where you’re signed in to Chrome with sync on.

Repeats every day, week, month or year, on chosen weekdays, or every few minutes between set hours
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Reminder App in Chrome’s side panel: today’s and tomorrow’s reminders, and a notification with Postpone and Dismiss

Reminder App’s form: a reminder to drink water every 30 minutes from 9 to 5, Monday to Friday

Where the numbers come from

EFSA, the European Food Safety Authority, set adequate intakes of total water in 2010: 2.0 liters a day for women and 2.5 liters for men, with 0.3 liters more in pregnancy and 0.7 liters more when breastfeeding. Total water includes the water in food, about a fifth, so drinks bring about 1.6 and 2.0 liters.
The US National Academies set adequate intakes in 2005 of 2.7 liters of total water a day for women and 3.7 for men, about 2.2 and 3.0 liters of it from drinks.

Both apply to healthy adults in mild weather with moderate activity. On a hot day or when you sweat, you need more. One way to see how much: weigh yourself before and after exercise. Each kilogram lost is about a liter of sweat to replace.

Spread it through the day

Set the hours you’re awake and Remind me to drink chimes for a glass at even intervals while this tab is open, from the first glass in the morning to the last in the evening.

Questions and answers

Why a range instead of one number?

The two best-known references differ. EFSA counts about 1.6 liters a day from drinks for women and 2.0 for men; the US National Academies count about 2.2 and 3.0. People who are well hydrated drink anywhere in that range, and more on hot days or when they sweat.

Does coffee or tea count?

Yes. Both references count all drinks, not only plain water. Food adds about a fifth more water on top.

Is this medical advice?

No. These are reference values for healthy adults. If a doctor has told you to drink more or less, for example for kidney or heart conditions, follow their advice.