How to use the Water Intake Calculator
- Enter your weight.
- Add your daily exercise time and climate.
- See your daily water target in liters, ounces and glasses.
- Optional: use the bottle planner with the estimate or a daily amount you choose.
How the target is calculated
We start with about 33 ml of water per kg of body weight (0.5 oz per lb), add roughly 350 ml for every 30 minutes of exercise, and add extra for hot or high-altitude climates and pregnancy. About 20% of daily water usually comes from food, so the drinking target is slightly lower than your total need.
Signs you are well hydrated
Pale yellow urine and rarely feeling thirsty are good signs. Coffee, tea and milk count toward your intake. Drinking far more than your body needs is unnecessary and, in extreme cases, dangerous.
This calculator gives general estimates for healthy adults and is not medical advice. Talk to a doctor or registered dietitian for personal guidance.
Frequently asked questions
Is 8 glasses a day right?
It is a reasonable rule of thumb (about 2 liters), but needs vary with body size, activity and climate.
Does coffee dehydrate you?
Not meaningfully for regular drinkers. Caffeinated drinks still contribute to daily fluid intake.