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Water Intake Calculator
Find your recommended daily water intake, based on your body weight and daily exercise time.
This tool provides a general estimate only and is not a substitute for professional medical advice; talk to a doctor about decisions affecting your personal health. If you have kidney disease, heart disease or another condition affecting fluid intake, ask your doctor what amount is right for you.
How much water do you actually need?
There's no single fixed answer for everyone, but nutrition references commonly suggest around 30–35 ml of water per kilogram of body weight per day for a healthy adult under normal conditions. This calculator uses the midpoint, 33 ml/kg, as a point estimate; for someone weighing 70 kg (about 154 lb), that works out to roughly 2,310 ml — a bit over two liters a day, before exercise.
Exercise increases that number because you lose more water through sweat. This tool adds about 350 ml for every 30 minutes of exercise, scaled proportionally for shorter or longer sessions. Heat, altitude, pregnancy and breastfeeding can also change your real needs, so treat this figure as a helpful starting point rather than a strict rule.
Frequently asked questions
Where does the 33 ml per kilogram formula come from?
Nutrition references typically suggest 30–35 ml of water per kilogram of body weight per day for healthy adults; this tool uses the midpoint, 33 ml/kg, as a point estimate.
Why does exercise increase water needs?
During exercise your body loses more water and electrolytes through sweat; this tool adds about 350 ml of water for every 30 minutes of exercise.
Do other drinks like tea or coffee count toward this total?
This figure is simply a general target for total daily fluids; beverages and water-rich foods both contribute toward it.
Does this apply during pregnancy or illness?
No — fluid needs change with pregnancy, breastfeeding, fever, illness and some medical conditions. Talk to a doctor for guidance specific to your situation.