Cups to Litres Converter
Convert cups to litres, choosing the cup volume explicitly. The default is the US customary cup; select 250 mL only when that is the cup size specified by your recipe.
Enter a zero or positive amount. Decimal values are supported. Only the displayed result is rounded.
The US cup factor follows the US customary relationship of 8 US fluid ounces per cup; NIST lists approximately 236.588 mL. The 250 mL option is a user-selected recipe volume, not a claim that all metric recipes use that cup size. See NIST volume conversion factors.
Formula
L = cups × mL per selected cup ÷ 1,000
Example: 2 US customary cups are about 0.473 L; two 250 mL cups equal 0.500 L.
About these units
Cup standards differ. This tool offers a US customary cup (236.5882365 mL) and a recipe-defined 250 mL cup; its reverse converter is specifically for US customary cups.
Everyday conversion examples
Enter the number of cups and choose the matching definition. The table shows why the cup convention matters when converting a recipe volume into litres.
| Cups | US customary (L) | Recipe-defined 250 mL (L) |
|---|---|---|
| 0.5 | 0.118 | 0.125 |
| 1 | 0.237 | 0.25 |
| 2 | 0.473 | 0.5 |
| 4 | 0.946 | 1 |
Examples are rounded for readability. Use the calculator above for another amount; it keeps the conversion factor until the final display.
What does this tool use by default?
It defaults to the US customary cup, approximately 236.5882365 mL, and offers 250 mL when a recipe specifies that size.
Why are two cups not always 0.5 L?
Two US customary cups are about 0.473 L. Two 250 mL cups equal 0.500 L. The result depends on the cup size selected.
Source
Conversion factors are based on customary and metric volume relationships documented by the National Institute of Standards and Technology (NIST), Guide to the SI, Appendix B.9. NIST reports rounded factors; this page displays a rounded result.