Daily Water Intake Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/5/2026
Recommended daily water intake is around 35 mL per kg of body weight at rest, more with physical activity. For a sedentary 70 kg person, that's about 2.45 L per day, including water and other beverages.
Explanation
This calculator estimates recommended daily water intake using a rule based on body weight: about 35 mL of water per kg at rest, a value consistent with the recommendations of the European Food Safety Authority (EFSA) and the American College of Sports Medicine (ACSM). This coefficient increases with physical activity level (up to 40-45 mL/kg for intense activity), since exertion and sweating raise water needs. This total corresponds to total water intake, not just water drunk by the glass: it includes other beverages and, to a lesser extent, the water contained in food (fruit, vegetables, soups...). This calculation doesn't account for factors that significantly raise actual needs: high heat, pregnancy, breastfeeding, fever, or certain medical conditions (kidney, heart) that can instead require water restriction. In these situations, a healthcare professional's advice always takes priority over this general estimate. For your daily calorie needs, see our calorie needs calculator.
Example: 70 kg, sedentary activity
Inputs
Weight: 70 kg. Activity level: sedentary (35 mL/kg).
Calculation
Water intake = (70 × 35) ÷ 1,000 = 2,450 ÷ 1,000 = 2.45.
Result
Recommended daily water intake is about 2.45 L.
Frequently asked questions
Does this total include only water drunk by the glass?
No, it corresponds to the total recommended water intake, which includes all beverages (water, tea, coffee, juice...) as well as the water provided by food, particularly water-rich fruits and vegetables (watermelon, cucumber, soup...). In practice, water drunk directly generally makes up 70 to 80% of this total, with the rest coming from food.
Should I drink more in hot weather?
Yes, sweating noticeably increases water losses in hot weather or during prolonged physical exertion, which raises actual needs beyond this baseline estimate. This calculator doesn't model ambient temperature: increase your intake accordingly during hot periods, and watch for signs of dehydration (intense thirst, dark urine, fatigue).
Does excessive water intake carry a risk?
Yes, drinking an amount of water far above actual needs over a short period can, in rare cases, excessively dilute blood sodium (hyponatremia), a documented risk notably among endurance athletes who drink well beyond their thirst. This estimate remains a reasonable average, not a minimum to systematically exceed.