Plot No. 47 · Health & Fitness
Daily Water Intake Calculator
Estimate how much water to drink per day from your body weight and exercise. It allows roughly 33 ml per kilogram of body weight, then adds about 0.35 litres for every 30 minutes of exercise, and converts the total into litres and 250 ml glasses.
This is total daily fluid, including drinks and water from food, and it does not adjust for heat or illness. It is an estimate, not medical advice.
The link saves your inputs so you can bookmark or share this exact result.
How your water target is worked out
This calculator estimates total daily fluid from two inputs. It allows about 33 ml of water per kilogram of body weight as a baseline, then adds roughly 0.35 litres for every 30 minutes of exercise to cover sweat losses. The two parts are added together to give a litres-per-day figure.
To make the number easier to act on, it also converts the total into 250 ml glasses by multiplying the litres by 1,000 and dividing by 250, then rounding. This total is all fluid for the day, so drinks like tea and coffee and the water in food all count toward it.
How to use the water intake calculator
- Enter your body weight in kilograms, which sets the baseline fluid need.
- Enter how many minutes of exercise you do on a typical day to add a sweat allowance.
- Read the daily target in litres and the rough number of 250 ml glasses, and adjust up in hot weather or illness.
Worked examples
Active adult
Inputs: 75 kg, 30 minutes of exercise
Result: About 2.83 litres per day, or roughly 11 glasses of 250 ml.
Lighter, sedentary day
Inputs: 60 kg, 0 minutes of exercise
Result: About 1.98 litres per day, or roughly 8 glasses of 250 ml.
Limitations and common mistakes
Edge cases and limitations
- It is a general estimate and does not adjust for heat, humidity, altitude, fever, pregnancy or breastfeeding, all of which raise needs.
- The total is all fluid, including drinks and water from food, not extra plain water to drink on top.
- Thirst and urine colour remain better real-time guides than any fixed daily figure.
Common mistakes
- Trying to drink the whole total as plain water when food and other drinks already supply a good share.
- Forgetting to raise intake on hot days or during long or intense exercise, when the fixed estimate falls short.
Frequently asked questions
How much water should I drink a day?
A common rule is about 33 ml per kilogram of body weight, plus extra for exercise. A 75 kg person doing 30 minutes of exercise gets roughly 2.48 litres from weight and 0.35 litres for the workout, totalling about 2.83 litres, or 11 glasses of 250 ml.
Does food count toward this total?
Yes. Around a fifth of most people's fluid comes from food, and tea, coffee and milk all count too. This figure is total fluid for the day, so you do not need to drink the whole amount as plain water on top of everything else.
When do I need more than this estimate?
Hot weather, intense or long training, illness with fever, pregnancy and breastfeeding all push needs higher. Thirst and urine colour are good real-time guides: pale straw is fine, dark yellow suggests you should drink more.
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