A common formula is 35 ml of water per kilogram of body weight. In imperial terms, that is roughly half your body weight in ounces. A 200-pound person would aim for about 100 ounces (3 liters) as a baseline, before activity adjustments.

Yes, but not as much as you might think. Muscle tissue contains about 75% water while fat tissue contains only 10%. People with more lean mass need slightly more water per pound, but the weight-based formula provides a practical approximation for everyone.

Your baseline needs stay consistent, but adjust upward on active days, in hot weather, or when consuming alcohol or caffeine. On rest days in cool weather, your baseline amount is sufficient. Listen to thirst signals as an additional guide.