Water Intake Calculator
A water intake calculator estimates how much water you should drink daily based on your body weight, using a widely cited baseline of about 35 ml per kilogram of body weight, plus an activity add-on for daily exercise. There is no single medical consensus figure for hydration since needs vary with climate and individual physiology, so this is a starting-point estimate rather than a prescription. Results are shown in liters, milliliters, and cups so you can match whatever units your water bottle uses.
Educational estimate only. Results are not medical, legal, or financial advice. Confirm important decisions with a qualified professional.
How it works
- Choose kilograms or pounds and enter your body weight.
- Enter your average daily exercise minutes.
- Read your recommended daily water intake in liters, ml, and cups.
Formula baseline = weight(kg) × 35 ml; + 350 ml per 30 minutes of daily exercise
Frequently asked questions
How much water should I drink per day?
A common baseline is about 35 ml per kilogram of body weight, plus more if you exercise. For a 70 kg person that is roughly 2.45 liters before activity is added.
Does exercise increase water needs?
Yes. This calculator adds about 350 ml for every 30 minutes of daily exercise to account for sweat loss.
Is the 8-glasses-a-day rule accurate?
It is a rough rule of thumb, not a scientific requirement. Needs scale with body size, climate, and activity, which is why this calculator uses body weight instead.
Does this count water from food and other drinks?
No, this estimates plain water intake only. Food and other beverages also contribute to total daily hydration.
Is this medical advice?
No. This is a general wellness estimate. People with kidney, heart, or other medical conditions should follow fluid guidance from their doctor.