Water Calculator
Estimate your daily water intake from body weight, exercise and climate in litres and glasses.
Daily water
2.7 L
In 250 ml glasses
11
Standard glass size
Millilitres
2,670 ml
Breakdown: 2,310 ml base + 360 ml exercise. Individual needs vary with sweat and health.
Last updated: February 2026
How this calculator is verified
Checked by True Calculator automated test suite on
- Formula verified against a published worked example in the automated test suite
- Edge cases (zero, negative, boundary and unit-mismatch inputs) covered by unit tests
The full verification method is on our how we verify page. Found an error? Tell us and we will re-check it.
When to Use This Calculator
Use this calculator when you want a concrete daily hydration target instead of vague 'drink more water' advice. Office workers who lose track of intake, runners and gym-goers adjusting for sweat, and families checking whether children and elders are drinking enough in summer all benefit from a number to aim for. The climate toggle matters for most of India, where heat raises fluid needs for several months of the year. Because the base is tied to body weight, the estimate scales naturally — a lighter person gets a smaller target and a heavier one a larger target. Pair the result with a bottle you carry everywhere, and hydration stops being guesswork.
How to Use This Calculator
- Step 1: Enter your body weight in kilograms to set the base water target.
- Step 2: Add the minutes of exercise or physical work you do on a typical day.
- Step 3: Select normal or hot climate depending on your city and season.
- Step 4: Read your total in litres, 250 ml glasses and millilitres, and track against it daily.
Worked Example
A 70 kg person who exercises for 30 minutes in a normal climate enters 70 and 30. The estimate is 33 ml per kilogram plus 12 ml per minute: 70 × 33 = 2310 ml base plus 30 × 12 = 360 ml for exercise, totalling 2670 ml, or 2.67 litres — about 11 standard glasses. In a hot climate the calculator adds 300 ml, bringing the total to 2970 ml. Reaching the target in a reusable bottle makes tracking simple.
Tips and Common Mistakes
- •Tip 1: Carry a 1 L bottle and refill it — a 2.5 L target becomes a simple count of refills.
- •Tip 2: Front-load your intake across the day instead of gulping litres at night.
- •Tip 3: After heavy sweat in Indian summers, add an extra glass or two beyond the estimate.
- ✗Mistake 1: Avoid treating the figure as a fixed rule for everyone — kidney conditions and medication change needs.
- ✗Mistake 2: Don't count only plain water while ignoring fluids from food, tea and buttermilk.
Frequently Asked Questions
How is my daily water requirement estimated?
The calculator uses a general guide of 33 ml per kilogram of body weight plus 12 ml per minute of daily exercise. A 70 kg person with 30 minutes of exercise gets about 2670 ml, or 2.67 litres.
Why does hot weather change my requirement?
In a hot climate you sweat more, so the calculator adds roughly 300 ml a day. This is a rough allowance — heavy outdoor work can push real needs higher.
Should I include tea, coffee and food?
Food and beverages contribute to your total intake. Plain water should still make up most of it, but the figure from this calculator is a total-fluid estimate, not just glasses of water.
How many glasses is 2.5 litres?
Using a standard 250 ml glass, 2.5 litres is exactly 10 glasses. The calculator reports both millilitres and the glass count so you can track by bottle or by glass.
Is drinking more water always better?
No. Needs vary with kidney health, medication and sweat. Very high intakes can strain the kidneys, so treat the result as a starting point and check with a doctor if you have health conditions.
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