Water Intake Calculator

Water Intake Calculator estimates a daily volume from body weight in kilograms and active minutes. It is a rough everyday figure, not medical advice.

35 ml per kilogram, plus 12 ml per minute

The form opens on 70 and 45. Base milliliters are weight times 35. Activity milliliters are the minutes, floored at zero, times 12. The total is those two parts added. Liters are the total divided by 1000. Cups divide the total by 240. For 70 and 45 the base is 2450, the activity part is 540, and the total is 2990. The screen lines are About 2,990 ml / day in a US locale, 2.99 liters, and about 12.5 cups (240 ml). Under them the page prints Rough everyday estimate — not medical advice. The button says Calculate. Last checked: October 2026, against waterIntake.

What the estimate leaves out

There is no climate field, no sweat rate, and no pregnancy or kidney input. A clinician's target can be higher or lower than 35 ml per kilogram. The activity term treats every minute the same, whether you walked or raced. Negative minutes are treated as zero. A weight of zero or below stops with Weight must be positive. The page does not convert pounds. If you know your weight in pounds, divide by 2.2 before you type, or the milliliters will be far too high. Cups here are 240 ml, not a kitchen cup of another size.

How to read the three lines

The milliliter line is the one to compare with a bottle size. 2990 ml is a little under three liter bottles. The liter line divides the total by 1000, so 2990 ml shows as 2.99 liters, and the cup line divides by 240 for about 12.5 cups. Weight is a kilogram field, and minutes are floored at zero, so a negative minute count adds nothing. The liter line is the same total with three digits of precision at two fraction digits. The cup line rounds to one fraction digit, so 12.458 cups prints as 12.5. Do not add the cup line on top of the milliliter line. They are the same water. Protein Intake Calculator and the macro tools answer food questions, not this volume.

When not to use the number

Do not use it as a prescription, a sports-drink plan, or a reason to ignore thirst and a doctor's limit. The comment in the formula calls it a rough everyday estimate. If you are told to restrict fluids, this page is the wrong place to set a target. A 60 kg person with 0 minutes is 2100 ml, because 60 times 35 is 2100 and the activity term is zero. An 80 kg person with 30 minutes is 2800 plus 360, which is 3160 ml. The weight and the minutes stay in this browser. A 90 kg person with 20 minutes is 3150 plus 240, which is 3390 ml, or 3.39 liters. That is the same two-part sum, only with a heavier weight and a shorter activity.