Water Intake Calculator

A common rule of thumb is about half to two-thirds of an ounce of water per pound of body weight per day (roughly 30–40 ml per kg), with more for exercise and hot weather. For many adults that lands near the familiar 8 cups (about 2 liters), but bigger and more active people need more.

It estimates a baseline from your body weight (about 0.5 oz per pound) and then adds extra for your activity level — roughly 12 oz for every 30 minutes of exercise. The result is shown in ounces, liters, and cups.

Yes. Despite the old myth, the mild diuretic effect of normal coffee and tea is outweighed by their water content, so they count toward your daily fluids. Water is still the best primary source because it has no calories or additives.

Pale-yellow urine and infrequent thirst are good signs you're well hydrated. Dark urine, persistent thirst, headaches, or fatigue can indicate you need more. Needs rise with heat, altitude, exercise, illness, pregnancy, and breastfeeding.

Yes, though it's rare. Drinking far more than your kidneys can excrete can dilute blood sodium (hyponatremia), which is dangerous. Spread intake through the day rather than forcing large volumes at once, and let thirst be your guide.