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How to understand your result
Your weight sets the starting range. You can then adjust for the weather and activity, add how long you exercised and log what you’ve already drunk. Use the result for everyday planning. How you feel and how much you sweat still matter.
The NHS starting point for daily fluids.
See a range for the day you’re planning.
Consider the drinks you’ve had, water in food and any personal medical advice.
What counts towards daily fluid intake?
Ordinary tea and coffee, milk, plain sparkling water and diluted drinks all count. Food supplies water too, so a figure for total water includes what you get from meals as well as drinks.
The drink checker shows which drinks count and what else to consider, such as caffeine, sugar or alcohol.
When your needs may change
Exercise, hot or humid weather, fever, vomiting and diarrhoea can increase fluid losses. Kidney, heart and liver conditions, pregnancy and some medicines can change what is safe. Follow individual clinical advice where it applies, and avoid trying to catch up by rapidly drinking a large volume.
For exercise, use the sweat rate calculator on a typical session. On an ordinary day, use the bottle and refill planner to see how often you might refill the bottle you use.
Daily water intake questions
How much water should I drink each day in the UK?
The NHS suggests six to eight cups or glasses of fluid a day as a general guide. You may need more when you’re active, in hot weather, unwell, pregnant or breastfeeding. You also get water from food and drinks other than plain water.
Is two litres of water a day enough?
Two litres may suit you on some days. How much you need depends on your size, how active you are, the weather and what you’re already eating and drinking.
Do tea, coffee and sparkling water count?
Yes. Ordinary tea, coffee and plain sparkling water all count towards your fluids. You can still consider things like caffeine, sugar and dental health when choosing a drink.
Can I drink too much water?
Yes. Drinking very large amounts quickly can dangerously dilute the sodium in your blood. Use the calculator figure as a guide and avoid forcing yourself to finish it.
Sources and methodology
Printable planner and conversion chart
Hydration conversion chart
Litres, millilitres, UK fluid ounces, US fluid ounces, metric cups and common bottle sizes.
Download the CSV chartPrintable daily planner
A simple one-page sheet for planning servings and recording what you actually drink.
Print or save a blank planner