BA Thread Calculator
Calculate British Association (BA) thread specifications commonly used in precision model engineering.
Thread Specifications
| Major Diameter: | - |
| Pitch: | - |
| Minor Diameter: | - |
| Tapping Hole Size: | - |
| Clearance Hole Size: | - |
Thread Profile Diagram
BA Thread Reference Table
| Size | Major Ø (mm) | Pitch (mm) | Tap Hole (mm) | Clearance Ø (mm) |
| BA 0 | 6.000 | 1.000 | 5.000 | 6.5 |
| BA 1 | 5.300 | 0.889 | 4.400 | 5.8 |
| BA 2 | 4.600 | 0.750 | 3.850 | 5.0 |
| BA 3 | 4.100 | 0.667 | 3.350 | 4.5 |
| BA 4 | 3.600 | 0.600 | 3.000 | 4.0 |
| BA 5 | 3.200 | 0.533 | 2.650 | 3.5 |
| BA 6 | 2.600 | 0.450 | 2.150 | 3.0 |
| BA 7 | 2.300 | 0.400 | 1.900 | 2.6 |
| BA 8 | 2.000 | 0.350 | 1.650 | 2.3 |
| BA 9 | 1.800 | 0.312 | 1.500 | 2.0 |
| BA 10 | 1.600 | 0.280 | 1.320 | 1.9 |
| BA 11 | 1.400 | 0.250 | 1.150 | 1.6 |