Question 1

How much water should I drink a day?

Accepted Answer

It depends on your size and activity, but a useful estimate is about 30–40 mL of fluid per kilogram of body weight. For reference, the U.S. DRI total-water targets are roughly 3.7 L/day for men and 2.7 L/day for women, including the water you get from food.

Question 2

Does coffee or tea count toward water intake?

Accepted Answer

Yes. Despite the old belief that caffeine is dehydrating, the fluid in coffee, tea, milk, and most drinks counts toward your daily total. Water and unsweetened drinks are still the best choice for hydration without added sugar.

Question 3

Should I really drink 8 glasses of water a day?

Accepted Answer

The '8 glasses' rule is a rough slogan, not an official guideline — and it's often too little once weight and activity are considered. Use your weight-based target as a starting point and adjust up in heat or with exercise.

Question 4

How do I know if I'm drinking enough?

Accepted Answer

Pale-yellow urine and infrequent thirst are good everyday signs. Dark urine, headaches, or fatigue can signal you need more, especially in hot weather or during exercise.

Water Intake Calculator — How Much Water Should You Drink a Day? (2026)