How much water should I drink a day?
For a 180 lb person who trains a few days a week (moderately active)
- Baseline (half your body weight in ounces)
- about 90 oz
- Adjusted for moderate activity
- about 108 oz a day
- In cups
- about 13 to 14 cups
- In liters
- about 3.2 liters
Opens the Water Intake. Free, no account needed.
Water is the least interesting habit on this whole site and one of the very few you can fix in a single day, which is a rare combination worth taking advantage of.
A simple starting point is about half your body weight in ounces, then a bit more if you are active or it is hot. For a 180 pound person who trains a few days a week, that works out to roughly 108 ounces a day, which is around 13 to 14 cups or about 3.2 liters. Heavier or more active means more, lighter or sedentary means less.
Why it is worth the small effort: research generally links even mild dehydration with worse strength and endurance, and most people are running a little under without realizing it. The fix costs nothing.
The practical version is to front-load it. Carry a bottle and sip through the day rather than remembering at 9pm and chugging a liter, which mostly just costs you sleep. Add electrolytes if you are training hard in heat.
Do not overthink this or chase a giant number. The target is a guideline, not a rule, and your body is good at telling you when you are short. Aim for the ballpark, spread it across the day, and move on to the things that matter more.
Put your weight and activity into the calculator for your own daily target.
Not sure where to start?
The home page calculator gives you your real numbers in one place: the calories to aim at, a macro split, and a few things to do this week. Free, no account needed to see it.
Find where to startIf you would rather someone build this around your life instead of guessing, my 1:1 coaching is there. The free tools get you most of the way.