Hydration guide
Water Intake Guide
Use a fluid estimate as a starting point, then adjust for climate, exercise, pregnancy, illness, diet and individual response.
Updated 16 October 2026 • Reviewed by Tools by Layna Editorial Team • General information only
Separate total water from drinks
A water reference can count both food and drinks, or drinks alone. Confusing those definitions can make two figures look contradictory. The Australian and New Zealand adult adequate intakes are 3.4 L total water and 2.6 L fluids for men, and 2.8 L total water and 2.1 L fluids for women. Fluids include drinks such as milk, not only plain water.
These are population adequate-intake references, not a quota every individual must force down. Food, body size, climate, exercise and health all change the practical context. Pregnancy and breastfeeding have separate reference values.
Worked example: count a drink log
A hypothetical log contains two 750 mL bottlefuls,300 mL of milk and 250 mL of another drink. The drink total is 750 ×2 +300 +250 =2,050 mL, or 2.05 L. Water in meals adds to total water but is not included in that drink log.
The log shows what was consumed; it does not prove adequacy or prescribe an extra amount. Use consistent definitions before comparing it with a reference value.
What the water calculator estimates
The Water Intake Calculator uses 35 mL per kilogram plus a fixed activity adjustment:500 mL if the selected activity factor is above 1.55, otherwise 250 mL. It does not measure sweat or accept climate and exercise-duration inputs. This product model is separate from the population adequate-intake table.
At 70 kg and an activity factor of 1.55, the model gives 70 ×35 +250 =2,700 mL. At a factor above 1.55 it gives 2,950 mL. A change in the displayed result reflects that preset, not an individual sweat test.
Adjust to actual conditions
Someone training outdoors in summer may need a different plan from the same person working indoors on a cool day. Consider actual duration, conditions and access to fluids instead of assuming one bottle count applies everywhere. Keep exercise hydration and electrolyte planning separate from the basic daily reference.
Thirst and urine appearance can add context but do not diagnose hydration or replace medical advice. Do not force excessive fluid to satisfy a calculator. Follow a clinician’s plan if you have a fluid restriction, relevant medication or a condition affecting fluid balance.
Frequently asked questions
Does tea, milk or another drink count?
The reference’s fluids column includes drinks, not only plain water. A drink log and total water including food are different totals.
Is the calculator’s result the official Australian reference?
No. The calculator uses a body-weight rule and a fixed activity increment. The official reference distinguishes fluids from food-and-fluid totals and uses population adequate intakes.
Can I use the same result for a long hot workout?
The tool does not measure sweat loss or session duration. A long or hot session needs additional context; use the separate training hydration guide and individual advice where appropriate.
Sources and method
- Australia and New Zealand water reference values — Definitions of total water and fluids, adequate intakes and excess-intake limitations.