Water Intake Calculator
This water intake calculator estimates how much water you should drink each day from your body weight, adjusted for activity level and climate, and shows the result in liters, fluid ounces, cups and glasses.
About this tool
This water intake calculator estimates how much water you should drink each day from your body weight, adjusted for activity level and climate, and shows the result in liters, fluid ounces, cups and glasses.
How to use it
- Enter your body weight in kg or lbs.
- Choose your usual activity level.
- Choose the climate you live in.
- Read your daily target in liters, fluid ounces and glasses.
Good to know
- The base amount is about 33 ml of water per kg of body weight — roughly 2.3 liters for a 70 kg adult.
- Activity adds up to 0.5 liters per day, and a warm or hot, humid climate adds up to another 0.5 liters.
- Water from food, tea, coffee and other drinks also counts toward daily fluid intake.
- The result is a general guideline; illness, pregnancy, breastfeeding and heavy sweating raise needs.
Runs entirely in your browser — nothing you enter is uploaded or stored.
Frequently asked questions
How much water should I drink a day?
A common estimate is about 30–35 ml per kg of body weight, which is roughly 2–2.5 liters for many adults before adding extra for exercise and heat. This calculator applies that rule to your own weight and conditions.
Does coffee or tea count toward water intake?
Yes. Tea and coffee still hydrate overall despite their caffeine, and water in food and other drinks counts too.
What are the signs I am not drinking enough?
Thirst, dark yellow urine, headaches and tiredness are common signs of low fluid intake. Pale yellow urine is a simple everyday indicator of good hydration.
Can you drink too much water?
Yes. Drinking very large amounts in a short time can lower blood sodium (hyponatremia), which is dangerous. Spread intake through the day and follow thirst, especially during long endurance events.