Daily Water Intake Calculator
How much water should you drink a day?
A general guide only. Needs rise in hot weather, illness or pregnancy — listen to your thirst.
About the Water Intake Calculator
Free water intake calculator. Estimate how much water to drink each day based on your body weight and activity level, in litres and cups.
Everything is calculated instantly in your browser — nothing you type is uploaded or stored. Bookmark Calcooly for the next time you need it.
How to use the Water Intake Calculator
- 1Choose units and enter your body weight.
- 2Add your daily exercise in minutes.
- 3See how much water to drink per day.
Frequently asked questions
How much water should I drink a day?+
A common guide is around 35 ml per kg of body weight, plus extra for exercise. This is a general estimate, not a strict rule.
Does the number change with activity?+
Yes — more exercise raises the recommendation to replace fluids lost through sweat.
Is the result exact?+
It's a reliable estimate for general information. For important financial, medical or legal decisions, check with a qualified professional.