If your value starts in mL, use mL to US fluid ounces. If it starts in US fluid ounces, use ounces to milliliters. Both convert volume, not ounces of mass.
The defined relationship is 1 US fl oz = 29.5735295625 mL. One form divides by that factor; the other multiplies. The mathematical operations are inverses, but copying a rounded answer back into the other form can lose digits.
Inputs and results
| mL to US fluid ounces | Ounces to milliliters | |
|---|---|---|
| Input | Nonnegative milliliters; default 500 | Nonnegative US fluid ounces; default 1 |
| Primary result | US fl oz, up to 12 decimal places | mL, up to 12 decimal places |
| Supporting outputs | Entered mL, US tablespoons, US cups | None |
| Default result | 16.907011350922 US fl oz | 29.5735295625 mL |
| Copy precision | Input and ounces up to 3 decimal places | Entered ounces up to 3 decimal places; mL result up to 12 |
The first form derives tablespoons as fluid ounces × 2 and cups as fluid ounces ÷ 8. Those detail rows show up to 3 and 4 decimal places, respectively. Its Copy output for 500 mL uses 16.907 US fl oz, rather than the longer primary readout.
Choosing the direction
Use the unit printed on your bottle, recipe or product-volume label as the source. Neither form uses the imperial fluid ounce or converts a mass ounce. A mass-to-volume conversion needs a material density and is a different task.
Rounding limits
The factor is defined exactly; calculation uses finite numerical arithmetic and formatting. “Up to 12 decimal places” describes the display, not 12 significant digits or added measurement accuracy. Preserve the original measurement if you need to check a conversion, and distinguish the primary result from the rounded Copy text.
Sources
NIST SP 811, unit definitions and Appendix B factors. The paired calculator controls and rounding described above are their current form behavior. NIST Handbook 44, Appendix C, customary unit relationships.