The famous "eight glasses of water a day" likely came from a 1945 recommendation that said we need about 64 ounces of total water intake daily. That includes water from food, coffee, and even that slice of watermelon you had. So if you’re slamming eight big glasses of just water, you might be overdoing it—or worse, making yourself miserable for no reason.
Your actual need depends on your body size, activity level, and the weather. A 120-pound desk worker in Maine isn’t the same as a 200-pound marathon runner in Phoenix. Duh, right?
So, what’s the real number for you?
Here’s a simple trick: take your body weight in pounds, divide it by two. That number is the minimum ounces of water you should aim for on a normal day. For me at 150 pounds, that’s 75 ounces. For Sarah at 130 pounds, that’s 65. See? Not 64 for everyone.
But hold on—this is your baseline, not a hard rule. I always add 8 to 16 ounces if I’ve exercised or if it’s hot outside. Your body is smart; it will tell you if you need more.
