Engineering DisclaimerEngineering calculations are provided for preliminary design and educational/reference purposes only. Users must verify all results according to applicable engineering standards, supplier data, manufacturing requirements, and professional engineering judgment.
Category: threads
Reference Dataset
Standard Thread Sizes (UNC/UNF & Metric) Table
Design parameters for metric coarse and unified national standard threads including pitch, major, pitch, and minor diameters.
Overview & Scope
Thread profiles detail pitch and root diameters for metric and unified national thread series. The tensile stress area dictates the thread's yield capacity under axial preload.
Technical Sizing Values
The table below specifies major, pitch, and minor diameters alongside nominal tensile stress areas.
| Thread Designation | Major Diameter (mm) | Major Diameter (in) | Pitch Diameter (mm) | Pitch Diameter (in) | Minor Diameter (mm) | Minor Diameter (in) | Tensile Stress Area (mm²) | Tensile Stress Area (in²) |
|---|---|---|---|---|---|---|---|---|
| M6 x 1.0 (Coarse) | 6 | 0.236 | 5.35 | 0.211 | 4.77 | 0.188 | 20.1 | 0.031 |
| M8 x 1.25 (Coarse) | 8 | 0.315 | 7.19 | 0.283 | 6.47 | 0.255 | 36.6 | 0.057 |
| M10 x 1.5 (Coarse) | 10 | 0.394 | 9.03 | 0.355 | 8.16 | 0.321 | 58 | 0.09 |
| M12 x 1.75 (Coarse) | 12 | 0.472 | 10.86 | 0.428 | 9.85 | 0.388 | 84.3 | 0.131 |
| 1/4-20 UNC | 6.35 | 0.25 | 5.54 | 0.218 | 4.74 | 0.187 | 20.5 | 0.032 |
| 3/8-16 UNC | 9.53 | 0.375 | 8.49 | 0.334 | 7.49 | 0.295 | 50 | 0.078 |
| 1/2-13 UNC | 12.7 | 0.5 | 11.43 | 0.45 | 10.16 | 0.4 | 91.5 | 0.142 |
Engineering Notes & Best Practices
- •Tensile stress area is a calculated cross-section that accounts for the helical thread pitch profile.
- •Metric coarse and UNC threads offer higher resistance to stripping in soft materials.
- •UNF fine threads provide finer adjustments and higher vibration loosening resistance.
Dataset Citations & References
ASME B1.1 Unified Inch Screw Threads
Public domain source and standard catalog reference parameters.
ISO 68-1 Thread Profiles
Public domain source and standard catalog reference parameters.