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Water Intake Calculator

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

Last reviewed: 5 September 2025Source: NHS — Health A-Z
Water Intake Calculator · AUHealth & Fitness

Rates & sources

Population-average body composition metrics. Always consult a qualified clinician before making health decisions.

Source: NHS — Health A-Z — figures refreshed at the start of each tax year.

When to use this calculator

  • Before setting a new health goal or checking whether a plan is realistic.
  • When you want to compare different assumptions without tracking them manually.
  • When you need a quick baseline before discussing the result with a professional.

A realistic Australia planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

Weight (kg)

80 kg

Activity Level (0=low, 1=moderate, 2=high)

5%

After entering these figures, compare daily water target and approx. glasses (250ml) before deciding which scenario looks strongest.

How to read your results

Daily Water Target

Use this metric to compare scenarios side by side and understand how the key drivers affect the final outcome.

Approx. Glasses (250ml)

Use this metric to compare scenarios side by side and understand how the key drivers affect the final outcome.

Method & assumptionsAuthoritative sources

Enter your body weight and activity level to calculate your recommended daily water intake. The base calculation uses 33ml per kg of body weight, with additional allowance for physical activity. Active individuals, those in hot climates, and pregnant or breastfeeding women typically need more. Remember that water from food (fruit, vegetables, soups) counts towards your daily total.

Common mistakes

  • !Using optimistic assumptions without testing a more cautious scenario as well.
  • !Comparing outputs from different tools without checking that the inputs match.
  • !Treating the result as a final quote instead of a planning estimate.

What to do next

  • Try at least one more scenario so you can compare a realistic range instead of a single estimate.
  • Use the related calculators below to cross-check the decision from another angle.
  • Open one of the linked guides if you need more context before you act on the result.

Frequently asked

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

Use arrow keys to navigate items, Enter or Space to expand/collapse.

End-of-article next steps

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