Water Intake Estimator

Rough daily fluid target based on body weight, adjusted for activity and hot climate.

Reviewed by Pooja V. Menon, Registered Dietitian · Last updated

How this is calculated

A common clinical shortcut is 30–35 ml of fluid per kg body weight for healthy adults as a baseline, with extra added for activity and hot weather. This agrees broadly with the European Food Safety Authority’s adequate intake of 2.0 L/day for women and 2.5 L/day for men and the US National Academies’ 2.7 L / 3.7 L figures, which include all sources of fluid — water, tea, milk, and water in foods.

  • Base: weight in kg × 32 ml
  • + 350 ml for moderate activity, + 700 ml for high
  • + 400 ml for hot/humid, + 800 ml for very hot

Roughly 20 % of daily fluid usually comes from food (fruit, vegetables, dal, curries). The rest should come from drinks — ideally mostly plain water.

Sources

  • EFSA Panel on Dietetic Products, Nutrition, and Allergies. Scientific Opinion on Dietary Reference Values for water. EFSA Journal 2010;8(3):1459.
  • Institute of Medicine (US). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. 2005.