View an illustrative daily fluid estimate based on body weight and an activity adjustment; personal needs can differ substantially.
Estimated Daily Fluid Intake
How the Hydration Estimate Is Calculated
This tool uses an illustrative baseline of 35 millilitres per kilogram of body weight and adds the activity adjustment selected on the page. The added amount is entered in US fluid ounces and converted to millilitres; the result is then shown in both US fluid ounces and metric units.
Fluid needs are individual
This simple estimate does not account for fluid from food, climate, sweating rate, illness, pregnancy, kidney or heart conditions, or medicines that affect fluid balance. It is not a universal daily requirement and should not override medical instructions.
Health note: Follow advice from your healthcare professional if you have a condition that affects hydration. Seek medical help for signs of severe dehydration or overhydration.
Example and limitations
The estimate is not a clinical hydration prescription. Fluid needs can change with climate, exercise, pregnancy, medicines, and health conditions; follow professional advice when fluid intake is medically restricted.
Source and important context
The National Academies explains that total water intake includes drinking water, other beverages, and moisture in food; individual needs vary with activity, climate, and health. National Academies: Dietary Reference Intakes for Water. This page provides general educational estimates, not a diagnosis or individualized care advice. Page information updated: 4 November 2026.