英制普通螺纹 (惠氏螺纹) -- 小螺纹系列 (BA)
| 名义尺寸 BA | 牙型代号 | 大径 mm d=D | 螺距 mm p | 每英寸牙数 tpi | 中径 mm d2=D2 | 小径 外螺纹 d3 | 牙型高 H1 | 底孔直径 mm |
| No. 14 | BA | 1.000 | 0.230 | 110.4 | 0.860 | 0.720 | 0.140 | 0.75 |
| No. 13 | BA | 1.200 | 0.250 | 101.6 | 1.050 | 0.900 | 0.150 | 0.95 |
| No. 12 | BA | 1.300 | 0.280 | 90.71 | 1.130 | 0.960 | 0.170 | 1.00 |
| No. 11 | BA | 1.500 | 0.310 | 81.93 | 1.315 | 1.130 | 0.185 | 1.20 |
| No. 10 | BA | 1.700 | 0.350 | 72.57 | 1.490 | 1.280 | 0.210 | 1.35 |
| No. 9 | BA | 1.900 | 0.390 | 65.12 | 1.665 | 1.430 | 0.235 | 1.50 |
| No. 8 | BA | 2.200 | 0.430 | 59.07 | 1.940 | 1.680 | 0.260 | 1.80 |
| No. 7 | BA | 2.500 | 0.480 | 52.92 | 2.210 | 1.920 | 0.290 | 2.00 |
| No. 6 | BA | 2.800 | 0.530 | 47.92 | 2.480 | 2.160 | 0.320 | 2.30 |
| No. 5 | BA | 3.200 | 0.590 | 43.05 | 2.845 | 2.490 | 0.355 | 2.60 |
| No. 4 | BA | 3.600 | 0.660 | 38.48 | 3.205 | 2.810 | 0.395 | 2.95 |
| No. 3 | BA | 4.100 | 0.730 | 34.79 | 3.660 | 3.220 | 0.440 | 3.40 |
| No. 2 | BA | 4.700 | 0.810 | 31.35 | 4.215 | 3.730 | 0.485 | 3.90 |
| No. 1 | BA | 5.300 | 0.900 | 28.22 | 4.760 | 4.220 | 0.540 | 4.40 |
| No. 0 | BA | 6.000 | 1.000 | 25.40 | 5.400 | 4.800 | 0.600 | 5.00 |