Water Intake Calculator & Tracker
Estimate a practical daily water goal from your weight, activity and climate -- in litres, glasses or bottles -- then track what you drink today with one-tap buttons. Your log stays in your browser.
Estimate your daily goal
Health note: This is an estimate, not a medical prescription. Hydration needs vary with climate, exercise, diet, pregnancy, age and health conditions. If you have kidney, heart or liver problems or have been advised to restrict fluids, follow your doctor's guidance.
Results
Estimated daily water goal
Millilitres
Glasses
Bottles
Today's water tracker
Set a goal above, or calculate one and choose “Use this as my daily goal”.
Drunk today
Remaining
Goal: not set
Logged today
Nothing logged yet today.
Your goal and today's log are saved only in this browser on this device (localStorage). Your weight is not saved. Nothing is sent to our servers.
How this calculator works
The estimate starts at about 33 ml per kilogram of body weight -- the middle of the commonly cited 30–35 ml/kg rule of thumb -- then adds about 250–1,000 ml for your daily activity level, about 350 ml for every 30 minutes of exercise, and 500 ml for hot or humid weather. The total is rounded to the nearest 50 ml and also shown in 250 ml glasses and your chosen bottle size. The tracker simply adds up what you log today against your goal; it resets automatically at midnight.
How much water do I need each day?
There is no single amount that suits everyone. Needs vary with body size, activity, climate, diet, pregnancy or breastfeeding, and health conditions. This calculator uses a common rule of thumb -- about 30-35 ml per kg of body weight -- plus allowances for activity, exercise and hot weather, to give a practical starting estimate. Thirst and pale-yellow urine are also useful everyday signs.
Does food and other drinks count?
Yes. Milk, tea, coffee, soups, fruit and vegetables all contribute to your daily water intake. Roughly a fifth of daily water typically comes from food, so you don't need to drink the whole estimate as plain water.
Where is my water log saved?
Only in your own browser, using localStorage on this device. It is never sent to our servers or included in analytics, and your body weight is not saved at all. Use Delete all data to remove it; clearing your browser data also removes it.
Can drinking too much water be harmful?
Yes. Drinking very large amounts in a short time can dilute the body's sodium (hyponatraemia). Spread intake through the day, and if you have kidney, heart or liver conditions or have been told to limit fluids, follow your doctor's advice rather than this estimate.
Disclaimer: This tool is for general information only and is not medical advice, diagnosis or treatment. See our Disclaimer and Terms of Use for more detail.