M12 Thread Specs
Standard: ISO 261 (ISO Metric Coarse)
This reference guide outlines the technical dimensions and tapping parameters for the standard M12 metric thread.
Part of the ISO Metric Coarse series defined by ISO 261, the thread features a nominal diameter of 12 mm and a pitch of 1.75 mm.
For machining or fabrication, the recommended tap drill size is 10.25 mm (for 75% thread depth) or 10.36 mm (for 65% thread depth).
Dimensional Specifications (mm)
Nominal Diameter
12 mm
Pitch
1.75 mm
Threads per mm
0.57
Major Diameter
12 mm
Pitch Diameter (d₂)
10.863 mm
Minor Diameter (d₁) Ext
10.106 mm
Minor Diameter (D₁) Int
10.358 mm
Thread Height
1.516 mm
Root Radius
0.253 mm
Drilling & Strength Specs
Tap Drill (75%)
10.25 mm
Tap Drill (65%)
10.36 mm
Stress Area
84.27 mm²
Stress Diameter
9.853 mm
Recommended Tightening Torque
| Property Class | Dry (Nm) | Lubricated (Nm) |
|---|---|---|
| Class 8.8 | 106 | 79.5 |
| Class 10.9 | 156 | 117 |
| Class 12.9 | 187 | 140.3 |
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Frequently Asked Questions
What is the tap drill size for a M12 thread?
For standard thread engagement (approx. 75%), the recommended tap drill size for M12 is 10.25 mm. For a slightly looser 65% thread engagement, a 10.36 mm drill bit is recommended.
What is the pitch of a M12 thread?
The thread pitch for a standard M12 thread is 1.75 mm, which equates to approximately 0.57 threads per millimeter.
What are the major and pitch diameters for M12?
The nominal major diameter of M12 is 12 mm. The calculated pitch diameter (d₂) is 10.863 mm per the ISO 68-1/ISO 261 standards.