Use this Water Intake Calculator to find your daily target. For most adults, aim for about 2.0 litres of water a day for women and 2.5 litres for men in total, including water from food and other drinks. Your exact need depends on your weight, activity and climate. Use the calculator below to work out your personal daily water intake in seconds.
Weight unit
General guidance: EFSA total water is about 2.0 litres a day for women and 2.5 litres a day for men; the US National Academies suggest about 2.7 litres for women and 3.7 litres for men (total water from drinks and food). About 20% of daily water comes from food.
How to Use This Calculator
- Enter your body weight. Type your weight and choose kg or lb.
- Choose your activity level and climate. Pick Sedentary, Light, Moderate or Very active, then Normal or Hot climate.
- Click Calculate Water Intake. The calculator shows your daily target in millilitres, litres, US fluid ounces, glasses of 240 ml and 500 ml bottles.
Worked example: For 70 kg, Moderate activity and Normal climate, the baseline is 70 x 35 = 2,450 ml, plus 700 ml for Moderate activity, giving 3,150 ml, or 3.15 litres a day.
If you leave the weight blank, or enter 0 or a negative number, the calculator will ask you to fill in all the fields with valid numbers. It will not show a result until you do.
Related calculators: TDEE Calculator, Calorie Deficit Calculator and Caffeine Cutoff Calculator.
Frequently Asked Questions
How much water should I drink per day?
General guidance: about 2.0 litres a day for women and 2.5 litres for men (EFSA total water), or about 2.7 litres for women and 3.7 litres for men (US National Academies, total water from drinks and food). Your exact need depends on weight, activity and climate.
Do coffee and tea count towards my water intake?
Yes, they mostly count as fluids, but water is the best choice; very high caffeine intake can make you urinate more, so do not rely on coffee alone.
How much extra water do I need in hot weather or when exercising?
Add roughly 500 ml for a hot day and more when you exercise hard or sweat a lot; drink before you feel very thirsty.
This calculator gives an estimate only and is not medical advice. If you have kidney disease, heart failure, or a prescribed fluid limit, follow your doctor’s advice.