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Water Intake Calculator

Calculate your recommended daily water intake based on weight and activity level.

Works the same in every country.

Your figures

Calculator inputs

When to use this calculator

  • Before setting a new health goal or checking whether a plan is realistic.
  • When you want a quick baseline before discussing the result with a professional.
  • When you are starting a fitness or diet programme and want a starting measurement.
  • When you want to recheck the numbers after several weeks of change.

A worked example

These are the example figures the calculator opens with.

A worked example
InputValue
Weight (kg)75
Activity Level (0=low, 1=moderate, 2=high)1

For those figures the calculator returns:

  • Daily water target: 2.80L
  • Approx. glasses (250ml): 11.00

Method & assumptions

Water intake calculators estimate your daily fluid requirements based on body weight, activity level, and in some cases climate. A common evidence-based method multiplies body weight in kilograms by 30โ€“35 ml to produce a baseline figure, with additional amounts added per hour of exercise. This approach is endorsed by various sports medicine and dietetic bodies as a practical starting point. It is important to remember that total fluid intake includes water from food and other beverages, not just plain water. Individual needs vary significantly โ€” kidney function, certain medical conditions, and medications can all affect how much fluid is appropriate. If you are managing a health condition, always seek guidance from a GP or registered dietitian before significantly increasing your fluid intake.

Common mistakes

  • Using an assumption that is not supported by a current local quote, bill, statement or official source.
  • Treating a generic estimate as a lender, provider, payroll or tax authority decision.
  • Mixing monthly and annual inputs without converting them consistently.
  • Testing only one scenario instead of checking how a cautious assumption changes the result.

What to do next

  • Run a second scenario with a cautious assumption so you can see the downside clearly.
  • Compare the result with the related calculators below before making a decision.
  • Check current local rules, eligibility and provider terms before applying or committing money.
  • Keep a record of the assumptions so you can update the estimate when a quote, bill or pay figure changes.

Keep exploring

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Questions people ask

A common guideline is 2โ€“3 litres per day, but actual needs depend on body weight, activity level, climate, and diet. This calculator gives a personalised estimate.