This list contains several (but by no means all) non-SI units and their SI equivalents. Many are archaic, but others are still in common usage.
| Name | Symbol | Value in SI Units |
|---|---|---|
| acre (US survey) | ac | 4046.873 m2 |
| angstrom | Å | 10-10 m |
| are | a | 1 dam2 |
| astronomical unit | ua | 1.49598 x 1011 m (approx.) |
| atmosphere | atm | 1.01325 x 105 Pa |
| atomic mass unit | u | 1.66054 x 10-27 kg (approx.) |
| bar | bar | 105 Pa |
| barn | b | 10-28 m2 |
| barrel (drum, 55 US gallons) | bbl | 208.4 L |
| calorie (international table) | cal | 4.1868 J |
| curie | Ci | 3.7 x 1010 Bq |
| day | d | 86,400 s |
| degree (angle) | ° | (π/180) rad |
| dyne | dyn | 10-5 N |
| electron volt | eV | 1.60218 x 10-19 J (approx.) |
| erg | erg | 100 nJ |
| fathom | fm | 1.8288 m |
| footcandle | fc | 10.764 lx |
| furlong | fur | 201.168 m |
| gallon (US liquid) | gal | 3.785 L |
| gauss | Gs | 10-4 T |
| hectare | ha | 1 hm2 |
| horsepower | hp | 745.7 W |
| hour | h | 3,600 s |
| inch | in | 2.54 cm |
| light year | ly | 9.46 Pm |
| liter | L | 1 dm3 |
| knot | kt | (1852/3600) m/s = .514 m/s (approx.) |
| metric ton (tonne) | t | 103 kg |
| minute (angle) | ' | (1/60)° = (π/10,800) rad |
| minute (time) | min | 60 s |
| nautical mile | nm | 1852 m |
| parsec | pc | 30.857 Pm |
| rad | rad | 1 cGy |
| rem | rem | 1 cSv |
| revolutions per minute | rpm | 10.472 mrad/s |
| roentgen | R | 2.58 x 10-4 C/kg |
| second (angle) | " | (1/60)' = (π/648,000) rad |
| yard | yd | 91.44 cm |