How this water intake calculator works
The calculator converts body weight to kilograms, multiplies by 30 mL and adds the selected activity and climate adjustments. The result is labelled as a rough drinking-water estimate.
Activity and climate adjustments
Activity and climate are broad add-ons for this rough heuristic. They do not model sweat rate, medical conditions, medications, endurance events or heat illness.
What this tool does not include
This calculator is not designed for children or teens, pregnancy, breastfeeding, fluid restriction, kidney disease, heart failure, heat illness, endurance events or medical conditions unless reviewed with a qualified professional. It should not be used for urgent symptoms or emergency decisions.
Key terms and assumptionsFormula notes, key terms, source assumptions and limits used in this calculator.
- Rough heuristic
- The baseline uses body weight in kilograms multiplied by 30 mL. It is a site heuristic, not an official recommended intake.
- Activity adjustment
- Low adds 0 mL/day, moderate adds 500 mL/day and high adds 1000 mL/day.
- Climate adjustment
- Temperate adds 0 mL/day, warm adds 250 mL/day and hot or humid adds 500 mL/day.
- Not a prescription
- This tool does not handle fluid restriction, heat illness, pregnancy, breastfeeding, children, endurance events or medical conditions.
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FAQs
Is this an official water recommendation?
No. It is a rough calculator heuristic based on entered values and assumptions.
Does food count toward water intake?
Total water can include drinking water, other beverages and water from food. The calculator output is labelled as a rough drinking-water estimate.
Why do activity and climate change the estimate?
Activity, heat and humidity can increase fluid losses, but the amount varies by person.
Can I use this if I have a medical condition?
No. Conditions and medications can affect fluid needs, so this calculator is not personal guidance.
Is this suitable during pregnancy or breastfeeding?
No. This calculator is not designed for pregnancy or breastfeeding.
Can children use this calculator?
No. This calculator is scoped to adults.
Can drinking too much water be a problem?
Fluid needs vary, and some people need limits. The calculator should not be used as a prescription.
Can I copy the result?
Yes. The copy summary includes the estimate, assumptions and limitation note.