How Much Water by Weight (kg & lbs)

Overview

There is no single universal ml/kg formula endorsed by all authorities. Two widely cited references are: the U.S. National Academies (NASEM) Adequate Intakes of about 3.7 L/day for men and 2.7 L/day for women (total water from foods + beverages) (NASEM, 2005 DRIs); and the European Food Safety Authority (EFSA) AIs of 2.5 L/day for men and 2.0 L/day for women (EFSA, 2010).

Both note that needs vary with environment, activity, and individual differences, and that roughly 20% of total water typically comes from foods (NASEM).

Our calculator uses a heuristic baseline proportional to body weight to produce personalized outputs within the ranges above. This heuristic is a product design choice and is not an official recommendation. Always follow clinical guidance for medical conditions.

Examples from this calculator (exact)

Example (calculator): weight 70 kg, age 25, exercise 0 h, 2500 kcal, climate: temperate. → Total need: 3150 ml (107 oz, 13 cups); from pure water: 2710 ml (92 oz, 11 cups); from food: 440 ml (15 oz, 2 cups). This text reflects the calculator's current logic.

Example (calculator): weight 80 kg, age 40, exercise 1 h, 2500 kcal, climate: temperate. → Total need: 4082 ml (138 oz, 17 cups); from pure water: 3642 ml (123 oz, 15 cups); from food: 440 ml (15 oz, 2 cups). This text reflects the calculator's current logic.

Next Steps

Open the hydration calculator and adjust weight, exercise hours, and climate for a personalized recommendation. Compare your total water with the AIs from NASEM or EFSA.