Water Intake Calculator

Use this daily water intake calculator to work out how much water to drink per day based on your weight, activity, and climate.

Takes under a minute to calculate your personalised daily hydration goal.

Start your hydration plan

Calculate your daily water target

Enter today's details to personalise your daily water requirement. All calculations run locally in your browser.

Essential inputs

Weight drives your base litres per day. Height is optional and only used to show a BMI reference.

Fine-tune adjustments

Optional fields to reflect today's activity level and climate so the water intake per day stays accurate.

Not a medical diagnosis. Seek advice if you are pregnant, breastfeeding, or managing a health condition.

Personalise your hydration plan

Share a few details to see today's recommended water intake per day and a schedule that spreads fluids across the day.

  • Enter your weight to set the how much water to drink per day calculation.
  • Optionally add height for BMI context and tweak climate or activity for precision.
  • Submit to unlock your litres per day goal, hydration schedule, and practical tips.

How we calculate your hydration plan

This calculator combines population hydration guidance with your personal inputs. The breakdown below explains each lever and the evidence we reference.

Key takeaways

Base litres come from a 35 ml per kg daily water intake formula used by dietitians.
Optional adjustments account for hotter days and longer workouts so your water requirement per day stays current.
Healthdirect Australia tips keep hydration habits and how much water to drink reminders front of mind.
Baseline from body weight

We multiply your weight by 35 ml to reflect dietetic guidance for healthy adults. The resulting total typically falls within the 2.7-3.7 L range highlighted by the U.S. National Academies and Mayo Clinic for women and men respectively.

Adjustments for gender, activity, and climate
  • Gender: Adds roughly 10% for male profiles to account for higher average total body water.
  • Exercise: Adds 0.5 to 1.0 litres depending on the activity level you select, mirroring hydration advice for sweat replacement.
  • Climate: Adds 0.3 to 0.5 litres whenever you indicate hot or dry conditions to offset environmental fluid loss.

These increments reflect guidance from Healthdirect Australia, Mayo Clinic, and published research on fluid needs during heat exposure and physical activity.

Daily schedule and tips

We distribute the total across five anchor moments. Early servings prime digestion and cognition, pre-meal water supports appetite cues, the post workout slot replaces sweat, and a lighter evening portion helps avoid sleep disruption.

Hydration guidance from Healthdirect Australia

Use these evidence-based reminders to keep water top of mind throughout the day.

Why water matters

  • Helps regulate body temperature, transport nutrients, and remove waste.
  • Supports mental focus, energy levels, and digestive health.

Spot dehydration early

  • Dark yellow urine, dry mouth, headache, or dizziness can signal low fluids.
  • Fatigue and trouble concentrating often improve with a glass of water.

What counts toward hydration

  • Water is the healthiest choice, but tea, coffee, and milk contribute to your total.
  • Limit sugary drinks and alcohol—these are not reliable hydration sources.
Source: Healthdirect Australia.
Evidence snapshot
  • Healthline (2024)

    Reviews how adequate hydration can modestly influence calorie burn and appetite while stressing that water alone is not a complete weight loss strategy.

    Read source>
  • Mayo Clinic (2022)

    Summarises daily fluid targets for adults and emphasises adapting intake for exercise, environment, illness, pregnancy, or breastfeeding.

    Read source>

Informational only; always personalise hydration goals with your healthcare professional, especially if you have medical conditions.

Water intake FAQs