Water Intake Calculator
Free water intake calculator. Estimate how much water you should drink each day in litres, millilitres, cups and ounces based on your body weight, exercise and climate.
About You
Daily Water Target
2.5 L
Other Measures
How It Works
Enter your weight
Choose metric or imperial units and type your body weight in kilograms or pounds.
Add exercise & climate
Enter how many minutes you exercise per day and select your climate so the estimate accounts for extra fluid loss.
See your target
Read your recommended daily water intake in litres, millilitres, cups, fluid ounces and glasses.
Water makes up roughly 60% of the adult body and is essential for temperature regulation, joint lubrication, digestion and delivering nutrients to cells. Daily needs vary with body size, activity level, climate, diet and overall health, which is why a single fixed number rarely fits everyone.
This water intake calculator estimates your daily target from your body weight, exercise minutes and climate, then expresses it in litres, millilitres, cups, ounces and glasses. The results are general estimates for healthy adults and are not medical advice — talk to a healthcare professional about your specific hydration needs.
Frequently Asked Questions
How much water should I drink a day?
A common starting point is about 35 millilitres of water per kilogram of body weight, with extra added for exercise and hot weather. This calculator uses that baseline, adds roughly 350 ml for every 30 minutes of activity, and multiplies by a climate factor to give a personalised estimate.
Does food count toward my water intake?
Yes. Around 20% of the fluid most people get comes from food, especially fruit and vegetables, and other drinks also contribute. This calculator estimates your total fluid target; you do not need to drink all of it as plain water, though water is the best choice.
How does exercise change my water needs?
You lose fluid through sweat during activity, so you need to replace it. The calculator adds about 350 ml of water for every 30 minutes of exercise. On long or intense sessions, especially in heat, you may need more along with electrolytes.
Can I drink too much water?
Drinking far more water than your body needs in a short time can dilute blood sodium, a rare but serious condition called hyponatraemia. The figures here are general estimates; spread intake through the day and consult a professional if you have a heart or kidney condition.
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