Thread Data
Metric Threads
| Diameter | Coarse (Standard) | Fine | Extra Fine | Superfine |
| M1 | 0.25mm | 0.2mm | ||
| M1.6 | 0.35mm | 0.2mm | ||
| M2 | 0.4mm | 0.25mm | ||
| M2.5 | 0.45mm | 0.35mm | ||
| M3 | 0.5mm | 0.35mm | ||
| M3.5 | 0.6mm | 0.35mm | ||
| M4 | 0.7mm | 0.5mm | ||
| M5 | 0.8mm | 0.5mm | ||
| M6 | 1mm | 0.75mm | ||
| M7 | 1mm | 0.75mm | ||
| M8 | 1.25mm | 1mm | 0.75mm | |
| M10 | 1.5mm | 1.25mm | 1mm | 0.75mm |
| M12 | 1.75mm | 1.5mm | 1.25mm | 1mm |
| M14 | 2mm | 1.5mm | 1.25mm | 1mm |
| M16 | 2mm | 1.5mm | 1mm | |
| M18 | 2.5mm | 2mm | 1.5mm | 1mm |
| M20 | 2.5mm | 2mm | 1.5mm | 1mm |
| M22 | 2.5mm | 2mm | 1.5mm | 1mm |
| M24 | 3mm | 2mm | 1.5mm | 1mm |
| M27 | 3mm | 2mm | 1.5mm | 1mm |
| M30 | 3.5mm | 3mm | 2mm | 1.5mm |
Imperial Threads
BA Thread Angle - 47.5 degrees
BSC (Cycle) Thread Angle - 60 degrees
BSF Thread Angle - 55 degrees
BSW (Whitworth) Thread Angle - 55 degrees
UNC Thread Angle - 60 degrees
UNF Thread Angle - 60 degrees
Screw Sizes
No.2 = 2.2mm
No.4 = 2.9mm
No.6 = 3.5mm
N0.7 = 3.9mm
No.8 = 4.2mm
No.10 = 4.8mm
No.12 = 5.5mm
No.14 = 6.3mm
TPI is 'Threads per Inch'
| Diameter | UNC TPI | UNF TPI | BSF TPI | BSC TPI | BSW TPI |
| No.0 | 80 | ||||
| No.1 | 64 | 72 | |||
| No.2 | 56 | 64 | |||
| No.3 | 48 | 56 | |||
| No.4 | 40 | 48 | |||
| No.5 | 40 | 44 | |||
| No.6 | 32 | 40 | |||
| No.8 | 32 | 36 | |||
| No.10 / 3/16" | 24 | 32 | 32 | 32 | 24 |
| No.12 | 24 | 28 | |||
| 1/4" | 20 | 28 | 26 | 26 | 20 |
| 5/16" | 18 | 24 | 22 | 26 | 18 |
| 3/8" | 16 | 24 | 20 | 26 | 16 |
| 7/16" | 14 | 20 | 18 | 26 | 14 |
| 1/2" | 13 | 20 | 16 | 26 | 12 |
| 9/16" | 12 | 18 | 16 | 26 | 12 |
| 5/8" | 11 | 18 | 14 | 26 | 11 |
| 3/4" | 10 | 16 | 12 | 26 | 10 |
| 7/8" | 9 | 14 | 11 | 26 | 9 |
| 1" | 8 | 12 | 10 | 26 | 8 |
| 1 1/8" | 7 | 12 | 9 | 7 | |
| 1 1/4" | 7 | 12 | 9 | 7 | |
| 1 3/8" | 6 | 12 | 8 | 6 | |
| 1 1/2" | 6 | 12 | 8 | 6 | |
| 1 3/4" | 5 | 5 | |||
| 2" | 4.5 | 4.5 | |||
| BA Screw Number | TPI | Diameter(") | |||
| 12 | 90.9 | 0.051 | |||
| 11 | 81.9 | 0.059 | |||
| 10 | 72.6 | 0.067 | |||
| 9 | 65.1 | 0.075 | |||
| 8 | 59.1 | 0.086 | |||
| 7 | 52.9 | 0.0982 | |||
| 6 | 47.9 | 0.11 | |||
| 5 | 47.9 | 0.126 | |||
| 4 | 38.5 | 0.142 | |||
| 3 | 34.8 | 0.161 | |||
| 2 | 31.4 | 0.185 | |||
| 0 | 25.4 | 0.236 |
Thread Names
BSF - British Standard Fine
BSC - British Standard Cycle, often simply referred to as 'Cycle' or 26TPI
BSW - British Standard Whitworth
BSP - British Standard Pipe
UNF - Unified National Fine
UNC - Unified National Coarse
BA - Britsh Association