Water Intake Calculator
Estimate your recommended daily water intake from your body weight.
For reference only; your own needs may differ.
How to use the Water Intake Calculator
- Enter your Weight (kg) in the single input box; the field takes kilograms, not pounds.
- Press Calculate for a daily target in litres, with the millilitre figure in brackets.
- Treat the number as a starting point and adjust it for heat, exercise and how you feel.
What 33 ml per kilogram covers and what it leaves out
The figure is body weight multiplied by 33 millilitres, a rule of thumb rather than a clinical prescription. It takes no account of age, climate, activity or medication, and it counts total fluid, so tea, coffee, soup and water-rich food all go towards it.
Daily targets by body weight
Straight arithmetic at 33 ml per kilogram, as this page reports it in litres and millilitres. Anyone whose condition affects fluid balance should follow their doctor rather than a formula.
| Weight | Millilitres | Litres |
|---|---|---|
| 55 kg | 1,815 | 1.8 |
| 60 kg | 1,980 | 2.0 |
| 70 kg | 2,310 | 2.3 |
| 80 kg | 2,640 | 2.6 |
| 90 kg | 2,970 | 3.0 |
Frequently asked questions
Where does the guideline come from?
It uses the common rule of roughly 33 ml per kilogram of body weight.
Do I need more when exercising?
Yes. Activity level, heat and humidity all raise your needs, and much of your intake also comes from food and other drinks.
How much water should I drink if I weigh 70 kg?
About 2.3 litres a day as a starting estimate, counting all fluids rather than plain water alone. Raise it in hot weather or after exercise.
Can I enter my weight in pounds?
No, the box expects kilograms. Divide pounds by 2.2 first: 154 lb is about 70 kg, which gives roughly 2.3 litres.
Do coffee and tea count towards the total?
Yes. Fluid from ordinary drinks and from food counts, so the target is not litres of plain water on top of everything else.