Water intake calculator
A daily water guide for your body weight, the exercise you do and the weather.
- 100% free
- No sign-up
- Runs in your browser
How to use Water intake calculator
- Enter your weight
- Add exercise and heat
- Read your target
About you
Minutes of activity that makes you sweat.
Water a day
Enter your weight to see how much water to drink.
Good to know
- All drinks count, including tea and coffee, and about a fifth of the water you take in comes from food.
- Pale yellow urine is a simple sign you’re drinking enough; thirst is a good guide for most healthy adults.
- If you have heart or kidney problems, or are pregnant or breastfeeding, ask your doctor how much to drink.
Next: Calorie calculator · BMI calculator · Unit converter
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How to use Water intake calculator
Enter your weight
Type your weight in kilograms or pounds. Heavier bodies need a little more water.
Add exercise and heat
Enter how many minutes you exercise on a typical day, and tick hot weather if it’s hot or humid where you are.
Read your target
See your daily water in litres or fluid ounces, as 250 ml glasses, and how much of it is for exercise and heat.
Why use Utils365
A clear rule
33 ml per kilogram of body weight, plus 350 ml for each 30 minutes of exercise and 500 ml in hot weather.
Litres, ounces and glasses
The same target in metric and US units, and as a count of 250 ml glasses to make it easy to follow.
Shows the breakdown
See what comes from your weight and what’s added for exercise and heat.
Private
Worked out in your browser; nothing you type is sent anywhere.
Frequently asked questions
How much water should I drink a day?
A common guide is about 33 ml per kilogram of body weight. At 70 kg that’s about 2.3 litres (78 fl oz), or roughly nine 250 ml glasses, before exercise.
How much extra water do I need when I exercise?
Around 350 ml for every 30 minutes of exercise, more if you sweat heavily. An hour at the gym adds about 0.7 litres to your day.
Do tea, coffee and food count?
Yes. Tea, coffee, milk and juice all count towards your fluids, and about a fifth of the water you take in comes from food such as fruit, vegetables and soup.
Is it the same as 8 glasses a day?
Eight 250 ml glasses is 2 litres, which is close for many adults. This calculator adjusts that for your weight, activity and climate.
How do I know if I’m drinking enough?
Pale yellow urine and rarely feeling thirsty are good signs. Dark urine, headaches and tiredness can mean you need more.
Can you drink too much water?
Yes, though it’s rare. Drinking several litres in a short time can dilute the salt in your blood. Spread drinks across the day and let thirst guide you.