Water Intake Calculator
Estimate how much water to drink from your weight and activity.
A hydration baseline
A simple, widely used rule ties daily water needs to body weight — about 35 millilitres per kilogram — with extra to replace what you sweat during exercise. It gives a sensible starting target.
A 70 kg person doing 30 minutes of exercise lands near 2.8 litres a day. Climate, illness, and pregnancy push that higher, and thirst plus urine color remain the best day-to-day check.
Simple and private
It applies the weight and activity rule in your browser, so your figures stay on your device.
Frequently Asked Questions
How is the estimate made?
It uses roughly 35 millilitres of water per kilogram of body weight, plus extra for exercise. It is a common baseline, not a medical prescription.
Does food count?
Food provides some fluid too, so total needs are often a little lower than a pure drinking target. Thirst and urine color are good real-world guides.
Do I need more in heat?
Yes. Hot weather, altitude, illness, and pregnancy all raise fluid needs beyond this baseline.
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