Water Intake Calculator: Metric vs Imperial Units
Convert body weight and water volume between metric and US customary units without mixing US and Imperial gallons.
Body-weight conversion
One kilogram is about 2.20462 pounds; one pound is 0.45359237 kg. The weight calculator converts pounds to kilograms before applying its 30–40 mL/kg/day heuristic. Enter the unit displayed on your scale and check the result label.
Water-volume quick reference
| Unit relationship | Conversion |
|---|---|
| Litres / millilitres | 1 L = 1,000 mL |
| Litres / US fluid ounces | 1 L ≈ 33.814 US fl oz |
| US fluid ounces / mL | 1 US fl oz ≈ 29.5735 mL |
| US customary cup | 1 US cup ≈ 236.588 mL |
| US liquid gallon | 1 US gal ≈ 3.785412 L |
| Imperial gallon | 1 Imp gal = 4.54609 L |
Avoid unit mix-ups
US fluid ounces measure volume; ounces by weight measure mass. US liquid gallons and Imperial gallons are different sizes. A cup may also follow a recipe-specific convention; this site labels US customary cups and a separate 250 mL recipe option. NIST volume factors.
Compare like with like
Confirm both quantities use the same dimension and unit system. The Converters hub and volume chart provide water-volume tools.
Common questions
Are US and Imperial gallons the same?
No. A US liquid gallon is about 3.785 L; an Imperial gallon is 4.54609 L.
Is an ounce always a fluid ounce?
No. Fluid ounces measure volume and ounces by weight measure mass.
What is a US customary cup?
Eight US fluid ounces, approximately 236.588 mL.
Sources and further reading
Sources support the specific guidance described above. This page is general information, not diagnosis or individualized medical advice.