Imperial and Metric Spanner Sizes
The following chart shows the AF spanner sizes that should be used with UNC and UNF thread imperial bolts, along with the metric equivalent spanner size.
| BOLT DIAMETER (INCHES) | AF SPANNER SIZE (INCHES) | SPANNER SIZE (MM) |
| 1/4 INCH | 6.35 MM | |
| 5/16 INCH | 7.94 MM | |
| 3/8 INCH | 9.52 MM | |
| 1/4 INCH | 7/16 INCH | 11.11 MM |
| 5/16 INCH | 1/2 INCH | 12.7 MM |
| 3/8 INCH | 9/16 INCH | 14.29 MM |
| 7/16 INCH | 5/8 INCH | 15.88 MM |
| 11/16 INCH | 17.46 MM | |
| 1/2 INCH | 3/4 INCH | 19.05 MM |
| 9/16 INCH | 7/8 INCH | 22.22 MM |
| 5/8 INCH | 15/16 INCH | 23.81 MM |
| 1 INCH | 25.40 MM | |
| 1.1/16 INCH | 26.93 MM | |
| 3/4 INCH | 1.1/8 INCH | 28.57 MM |