| 螺紋環規(美制螺紋UNC、UNF) | ||
| 美制牙(UNC、UNF): 1級牙寫法→3B，2級牙寫法→2B，3級牙寫法→1B | ||
| -- | -- | 1" UNS 14 |
| -- | -- | 1/4 UNEF 32 |
| -- | -- | -- |
| NO.04 UNC 40 | -- | 1/4 UNS 36 |
| NO.05 UNC 40 | NO.06 UNF 40 | 1/4 UNS 40 |
| NO.06 UNC 32 | NO.08 UNF 36 | 5/16 UNEF 32 |
| NO.08 UNC 32 | NO.10 UNF 32 | 3/8 UNEF 32 |
| NO.10 UNC 24 | NO.12 UNF 28 | 7/16 UNS 24 |
| NO.12 UNC 24 | 1/4 UNF 28 | 7/16 UNS 27 |
| 1/4 UNC 20 | 5/16 UNF 24 | 7/16 UNEF 28 |
| 5/16 UNC 18 | 3/8 UNF 24 | 1/2 UNEF 28(32) |
| 3/8 UNC 16 | 7/16 UNF 20 | 9/16 UNEF 24(30) |
| 7/16 UNC 14 | 1/2 UNF 20 | 5/8 UNEF 24 |
| 1/2 UNC 13 | 9/16 UNF 18 | 11/16 UNEF 24 |
| 9/16 UNC 12 | 5/8 UNF 18 | 3/4 UNEF 20 |
| 5/8 UNC 11 | 3/4 UNF 16 | 7/8 UNEF 20 |
| 3/4 UNC 10 | 7/8 UNF 14 | 1" UNEF 20 |
| 7/8 UNC 9 | 1" UNF 12 | |
| 1" UNC 8 | -- | |