美制螺丝规格对照表如下：
美制外螺纹（2A）常用螺丝规格极限尺寸表（粗牙）
| 公称尺寸 | 螺纹系 | 大径 | 中径 | 小径 | 每英寸牙数 | 螺胚直径 |
| --- | --- | --- | --- | --- | --- | --- |
| 8-32 | UNC | 0.157 | 0.163 | 0.1399 | 0.1428 | 0.1248 | 3.58 | 3.61 |
| 10-24 | UNC | 0.1818 | 0.189 | 0.1586 | 0.1619 | 0.1379 | 4.6177 | 4.8006 |
| 12-24 | UNC | 0.2078 | 0.215 | 0.1845 | 0.1879 | 0.1639 | 5.2781 | 5.461 |
| 1/4-20 | UNC | 0.2408 | 0.2489 | 0.2127 | 0.2164 | 0.1876 | 6.1163 | 6.3221 |
| 3/8-16 | UNC | 0.3643 | 0.3737 | 0.3287 | 0.3331 | 0.297 | 9.2532 | 9.4928 |
| 7/16-14 | UNC | 0.4258 | 0.4361 | 0.3850 | 0.3897 | 0.3485 | 10.8153 | 11.0769 |
| 1/2-13 | UNC | 0.4876 | 0.4985 | 0.4435 | 0.4485 | 0.4041 | 12.3851 | 12.6619 |
| 12-32 | UNEF | 0.2150 | 0.2164 | 0.1879 | 0.1900 | 0.1640 | 12.4612 | 12.5524 |
美制外螺纹（2A）常用螺丝规格极限尺寸表（细牙）
| 公称尺寸 | 螺纹系 | 大径 | 中径 | 小径 | 每英寸牙数 | 螺胚直径 |
| --- | --- | --- | --- | --- | --- | --- |
| 8-36 | UNF | 0.1577 | 0.1632 | 0.1424 | 0.1452 | 0.1291 | 3.65 | 3.67 |
| 10-32 | UNF | 0.1818 | 0.1890 | 0.1586 | 0.1619 | 0.1379 | 4.6177 | 4.8006 |
| 12-32 | UNEF | 0.2150 | 0.2164 | 0.1879 | 0.1900 | 0.1640 | 12.4612 | 12.5524 |
| 1/4-28 | UNF | 0.2408 | 0.2489 | 0.2127 | 0.2164 | 0.1876 | 6.1163 | 6.3221 |
| 3/8-24 | UNF | 0.3643 | 0.3737 | 0.3287 | 0.3331 | 0.297 | 9.2532 | 9.4928 |
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