Water Intake Calculator
Calculate how much water to drink daily based on body weight and activity. Stay hydrated with personalised daily targets.
Daily water
2.7 L
In 250 ml glasses
11
Standard glass size
Millilitres
2,670 ml
General guide: 33 ml per kg of body weight plus 12 ml per minute of exercise. Individual needs vary with climate, sweat and health.
How it works
Litres = weight kg × 0.033 + exercise minutes × 0.012.
Example: 70 kg + 30 min exercise → ≈ 2.67 litres.
Last updated: August 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 the water intake calculator when you want a personal hydration target rather than the generic 'eight glasses' advice, which often falls short in Indian summers. Enter your weight and activity level to get a daily total in litres, and adjust for hot climates if you live somewhere with long dry seasons. Runners and gym-goers use it to plan fluids around workouts, office workers use it to beat afternoon sluggishness, and parents use it to check whether children are drinking enough during school days and summer holidays. Because the estimate scales with body weight, it updates naturally as you gain or lose weight. Keep a marked bottle at your desk or in your bag, and track your intake against the target through the day.
How to Use This Calculator
- Step 1: Enter your current body weight in kilograms.
- Step 2: Enter the minutes of exercise or physical activity you do in a typical day, or 0 if none.
- Step 3: Calculate and read your target in litres, millilitres and 250 ml glasses.
- Step 4: Spread that total across the day instead of drinking it at once.
Worked Example
A 28-year-old runner in Bengaluru who weighs 60 kg and exercises for 30 minutes a day enters both numbers. The calculator uses about 33 ml per kilogram of body weight plus 12 ml per minute of activity, giving 1,980 ml plus 360 ml, or about 2.34 litres a day. That equals roughly nine 250 ml glasses. The target rises in summer, during long commutes in the heat or on heavier training days, so treat the figure as a baseline and drink more when you sweat more. Other fluids also count toward the total.
Tips and Common Mistakes
- •Tip 1: In hot Indian summers or during outdoor commutes, add extra glasses on top of the calculated target, since sweat loss is higher.
- •Tip 2: Carry a 1-litre bottle and mark it twice a day, which makes a 2-litre target much easier to hit than relying on memory.
- •Tip 3: Check the colour of your urine as a rough guide; pale yellow usually means you are adequately hydrated.
- ✗Mistake 1: Entering exercise minutes as hours, which adds far more water than intended and inflates the daily target.
- ✗Mistake 2: Drinking the whole day's target in one sitting, which is not how the body absorbs water and can cause discomfort.
Frequently Asked Questions
How much water should I drink a day?
A common guide is 33 ml per kg of body weight, plus extra for exercise and hot climates. A 70 kg person needs about 2.3 litres at rest.
Does food count toward water intake?
Yes. Food provides roughly 20% of daily water, so drinks alone need only about 80% of the total target.
Can I drink too much water?
Drinking far beyond your needs is possible but rare. Your kidneys handle about 1 litre per hour; very large intakes can cause water intoxication.
Do I need more water in summer or when exercising?
Yes. Sweat increases in heat and during exercise, so add roughly 12 ml per minute of activity and drink extra on hot days or when your urine is dark.
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