Volume conversion starts with the cubic meter
CalcOS relates every volume unit to the cubic meter. A liter is exactly 0.001 cubic meter and a milliliter is exactly one cubic centimeter. Customary liquid units use their specific legal definitions.
Keeping variants in the unit ID prevents the common mistake of treating US and Imperial gallons—or different regional cups—as interchangeable.
Supported liquid and cubic units
| Unit | Exact relationship | System |
|---|---|---|
| milliliter | 0.001 liter | metric |
| liter | 0.001 m³ | metric |
| US fluid ounce | 29.5735295625 mL | US customary liquid |
| US customary cup | 236.5882365 mL | US customary |
| US liquid gallon | 3.785411784 L | US customary liquid |
| imperial gallon | 4.54609 L | Imperial |
Liquid measure versus dry measure
US liquid gallons and related liquid units do not define US dry gallons, dry quarts, or dry pints. CalcOS keeps dry-volume families separate so the name and definition remain visible.
Cooking cups vary
A “cup” can mean a US customary cup, US legal nutrition cup, metric cup, imperial cup, or another regional measure. The Express converter labels its supported cup as US customary cup; it never presents an unlabeled cup.
Popular volume converters
- Liters to US Liquid Gallons Converter
- US Liquid Gallons to Liters Converter
- Milliliters to US Customary Cups Converter
- US Customary Cups to Milliliters Converter
Authoritative references: BIPM SI Brochure and NIST Handbook 44, Appendix C.