Water Intake Calculator
Choose your group and add your exercise. The page shows the total water you need, how much to drink and what that looks like in glasses.
This is an estimate for general information and is not medical advice. Needs change with weather, illness and some medicines, so follow your doctor if they have given you specific advice.
Worked examples
Woman, 1 hour exercise
Female, not pregnant, 1 hour of exercise
2.5 litres in total, 2.0 litres from drinks
2.0 + 0.5, then 80% from drinks.
About Water Intake Calculator
How much should you drink in a day? The European Food Safety Authority sets an adequate intake of total water for adults at 2.5 litres for men and 2.0 litres for women. That figure includes water from food, which usually supplies about a fifth, so the rest comes from drinks. The NHS suggests 6 to 8 glasses of fluid a day, which fits comfortably within this.
This calculator starts from the figure for your group and adds 0.5 litres for each hour of exercise. Pregnancy raises the starting figure to 2.3 litres and breastfeeding to 2.7. You get the total, the amount to drink and a count of 200 millilitre glasses. Tea, coffee, milk and juice all count. This is an estimate and not medical advice.
How to use Water Intake Calculator
- Choose male or female. If female, say whether you are pregnant or breastfeeding.
- Enter the hours of exercise you do in a typical day.
- Read the total water, the drinks figure and the number of glasses.
- Spread the drinks over the day.
Common uses
- Setting a daily drinking goal
- Adjusting for a harder training week
- Planning for pregnancy or breastfeeding
- Working out how many bottles to carry in a day
Frequently asked questions
How much water should I drink a day?
The EFSA adequate intake of total water is 2.5 litres for men and 2.0 litres for women. About 80% usually comes from drinks, so around 2.0 litres for men and 1.6 litres for women. The NHS suggests 6 to 8 glasses of fluid.
Do tea and coffee count?
Yes. The NHS says lower-sugar drinks, including tea and coffee, count towards your daily total. Water, milk and other non-alcoholic drinks all help. Alcohol does not.
How much extra do I need when I exercise?
A common guide is 0.4 to 0.8 litres for each hour of hard exercise, depending on sweat and heat. The page adds 0.5 litres per hour as a middle figure. In hot weather or for long sessions you may need more.
How do I know if I am drinking enough?
Pale yellow urine in the day is a simple sign. Thirst is also a good guide for most healthy adults. Check with your GP if you feel unusually thirsty or have a condition that affects fluids.
Can I drink too much water?
It is rare, but drinking very large amounts quickly can be harmful. Sip through the day. If your doctor has told you to limit or increase fluids, follow their advice. This is an estimate and not medical advice.