A fluid ounce (abbreviated fl oz, fl. oz. or oz. fl., old forms ℥, fl ℥, f℥, ƒ ℥) is a unit of volume (also called capacity) typically used for measuring liquids. Various definitions have been used throughout history, but only two are still in common use: the British Imperial and the United States customary fluid ounce. An imperial fluid ounce is 1⁄20 of an imperial pint, 1⁄160 of an imperial gallon or approximately 28.4 ml. A US fluid ounce is 1⁄16 of a US fluid pint and 1⁄128 of a US liquid gallon or approximately 29.57 ml, making it about 4% larger than the imperial fluid ounce.
US customary fluid ounce
| 1 US fluid ounce | = | 1⁄128 | US gallon |
| = | 1⁄32 | US quart | |
| = | 1⁄16 | US pint | |
| = | 1⁄8 | US cup | |
| = | 1⁄4 | US gill | |
| = | 2 | US tablespoons | |
| = | 6 | US teaspoons | |
| = | 8 | US fluid drams | |
| = | 1.8046875 | cubic inches | |
| = | 29.5735295625 | millilitres | |
| ≈ | 1.040842731 | imperial fluid ounces |
| Definition | Relation to SI units |
|---|---|
≡ 1⁄128 gal (US) |
| US legal cup | pipe | drop (imperial) | pony | imperial minim | fluid scruple | petaliter | hectoliter |
|---|---|---|---|---|---|---|---|
| 1 | 0.0005032 | 2,432.6839108 | 10.8204873 | 4,054.4731847 | 202.7236592 | 2.4 × 10-16 | 0.0024 |
| 1,987.3411866 | 1 | 4,834,572.929895 | 21 504 | 8,057,621.5498223 | 402,881.0774932 | 4.76961884784 × 10-13 | 4.7696188 |
| 0.0004111 | 2.0684350293206 × 10-7 | 1 | 0.0044480 | 1.6666667 | 0.0833333 | 9.86564670138 × 10-20 | 9.86564670138 × 10-7 |
| 0.0924173 | 4.6502976190476 × 10-5 | 224.8220299 | 1 | 374.7033831 | 18.7351692 | 2.2180147171875 × 10-17 | 0.0002218 |
| 0.0002466 | 1.2410610175928 × 10-7 | 0.6000000 | 0.0026688 | 1 | 0.0500000 | 5.91938802083 × 10-20 | 5.91938802083 × 10-7 |
| 0.0049328 | 2.482122035173 × 10-6 | 12.0000000 | 0.0533756 | 20.0000000 | 1 | 1.18387760416 × 10-18 | 1.18387760416 × 10-5 |
| 4.1666666666667 × 1015 | 2 096 603 590 144 | 1.0136182961631 × 1019 | 4.5085363602457 × 1016 | 1.6893638269379 × 1019 | 8.4468191347325 × 1017 | 1 | 10 000 000 000 000 |
| 416.6666667 | 0.2096604 | 1,013,618.2961631 | 4,508.5363602 | 1,689,363.8269379 | 84,468.1913473 | 1.0 × 10-13 | 1 |
| Symbol | Definition |
|---|---|
| ≡ | exactly equal |
| ≈ | approximately equal to |
| = | equal to |
| digits | indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …) |
| 1 US fluid ounces | = 2.95735295625E-5 cubic meters |
| 2 US fluid ounces | = 5.9147059125E-5 cubic meters |
| 3 US fluid ounces | = 8.87205886875E-5 cubic meters |
| 4 US fluid ounces | = 0.00011829411825 cubic meters |
| 5 US fluid ounces | = 0.0001478676478125 cubic meters |