💧 Water Intake Calculator

How much water you should drink daily — based on weight, exercise and climate

kg
min

Your Hydration Target

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litres per day
In Glasses (250ml)—
In Pints—
💡 All fluids count toward hydration — tea, coffee, milk and food (≈20% of intake comes from food). The NHS suggests 6–8 glasses of fluid daily as a general guide.

How Much Water Do You Need?

A common guideline is around 30–35ml per kg of body weight daily, adjusted upward for exercise (add ~350ml per 30 minutes) and hot conditions. For a 75kg adult, that's roughly 2.3–2.6 litres of total fluid per day.

NHS Guidance

The NHS Eatwell Guide recommends 6–8 cups or glasses of fluid a day — water, lower-fat milk, sugar-free drinks, tea and coffee all count. You need more in hot weather or when exercising.

Signs of Dehydration

Dark yellow urine, thirst, dry mouth, tiredness and headaches are early signs. Urine should be pale straw-coloured. Older adults are at higher risk as the thirst response weakens with age.

Can You Drink Too Much?

Yes — though it's rare. Drinking many litres in a short period can cause hyponatraemia (low blood sodium). Spread intake through the day rather than drinking large volumes at once.