Water Intake Calculator
Estimate how much water to drink a day from weight, exercise and climate.
How to use the Water Intake Calculator
- 1Enter your body weight in kilograms or pounds.
- 2Set your daily exercise, the climate and pregnancy if it applies.
- 3Read your daily water target and a drinking schedule for the day.
About Water Intake Calculator
The Water Intake Calculator estimates how much water to drink each day. It starts from your body weight at 33 ml per kilogram (about half an ounce per pound), adds 350 ml for every 30 minutes of exercise, 0.5 or 1 liter for warm or hot weather, and extra water during pregnancy (300 ml) or breastfeeding (700 ml). The result is shown in liters or US fluid ounces, with the other unit alongside.
Choose a glass or bottle size, from 200 ml to a 500 ml bottle or from 8 to 20 fl oz, to see how many glasses that is. With the schedule turned on, the calculator spreads the glasses evenly between your wake-up time and an hour before bed, rounded to the quarter hour, with the running total for each one. The plan can be copied. The base, exercise and climate parts are listed separately so you can see where the total comes from.
It helps people who want to drink more regularly, athletes on training days, travelers in hot climates and pregnant or breastfeeding women. Runners can combine it with the Running Pace Calculator to estimate how long they will be out, and the BMI & Calorie Calculator covers daily calorie needs.
Frequently asked questions
How much water should I drink a day?
A common guideline is about 33 ml per kilogram of body weight, which is about 2.3 liters for a 70 kg adult, plus extra for exercise and heat. Health authorities put total water intake at about 2 liters a day for women and 2.5 liters for men, including water from food.
How much extra water do I need when exercising?
About 350 ml, or 12 oz, for every 30 minutes of exercise is a common rule. In hot weather or for long, sweaty sessions you may need more; weighing yourself before and after training shows how much you lost.
How many glasses of water a day is that?
With 250 ml glasses, 2.5 liters is 10 glasses. The familiar 8 × 8 rule, eight 8-ounce glasses, is 1.9 liters.
Do coffee, tea and food count toward water intake?
Yes. Tea and coffee count despite their mild diuretic effect, and food provides about a fifth of daily water. This calculator estimates what to drink on top of food.
More in Health & Fitness
Work out running pace, finish time or distance, with splits and speed for any race.
Find the best time to go to bed or wake up based on 90-minute sleep cycles.
Estimate your due date, current pregnancy week, trimester and key milestones.