How to use this water intake calculator
- Body weight, enter your weight and pick kilograms (kg) or pounds (lb).
- Exercise, enter how many minutes you train or move on a typical day.
- Climate, choose Normal or Hot depending on the weather where you are.
- Read your daily water target in litres, cups and fluid ounces, it updates instantly as you type.
Nothing is submitted or stored: the numbers never leave your device, so you can check yours and your family's figures privately.
How daily water intake is estimated
The starting point is your body weight. A widely used guide is about 30 to 35 ml of water per kilogramof body weight, and this calculator uses roughly 33 ml per kg as a middle figure. So a 70 kg adult begins at around 2.3 litres a day. If you enter pounds, your weight is converted to kilograms first.
Exercise raises your needs because you lose fluid through sweat. A practical rule is to add roughly350 to 500 ml for every 30 minutes of activity, and this tool adds about 350 ml per 30 minutes on top of your baseline. Hot weather pushes the figure up again, so selecting a Hot climate adds about 10 percent more to account for extra sweating. The result is shown three ways: litres, US cups at 237 ml each, and US fluid ounces at 29.57 ml each.
Remember that food and other drinks count toward this total, so you do not have to reach the whole figure from plain water alone. Thirst, urine colour and how you feel are good day-to-day signals, and your needs can shift with activity, altitude and health.
A general estimate, please read
This calculator gives a general estimate, not a personal prescription. Individual needs vary with age, sex, body composition, activity, diet and the weather, and some health conditions change how much fluid is safe to drink. Use the number as a sensible starting target rather than an exact rule.
Medical disclaimer: This calculator is for general information only and is not medical advice. It cannot account for individual medical conditions such as kidney or heart problems or pregnancy. Always consult a qualified doctor or healthcare professional about your hydration and health.
Frequently asked questions
How much water should I drink per day?
A common guide is about 30 to 35 ml per kilogram of body weight, so a 70 kg adult starts at roughly 2.3 litres a day before adding extra for exercise or heat.
Does exercise change how much I need?
Yes. Add roughly 350 to 500 ml for every 30 minutes of exercise to replace fluid lost through sweat. This tool adds about 350 ml per 30 minutes.
Should I drink more in hot weather?
Usually yes, because heat increases sweating. Selecting Hot adds about 10 percent to your baseline, but drink more if you feel thirsty.
Do food and other drinks count?
Yes, tea, milk, juice and water-rich foods all contribute, so part of your daily target is met through what you eat and drink.
Is my data uploaded?
No, everything is calculated on your device and nothing is sent anywhere.