M12x1.25 Thread Specs
Standard: ISO 261 (ISO Metric Fine)
This reference guide outlines the technical dimensions and tapping parameters for the standard M12x1.25 metric thread.
Part of the ISO Metric Fine series defined by ISO 261, the thread features a nominal diameter of 12 mm and a pitch of 1.25 mm.
For machining or fabrication, the recommended tap drill size is 10.75 mm (for 75% thread depth) or 10.83 mm (for 65% thread depth).
Dimensional Specifications (mm)
Nominal Diameter
12 mm
Pitch
1.25 mm
Threads per mm
0.8
Major Diameter
12 mm
Pitch Diameter (d₂)
11.188 mm
Minor Diameter (d₁) Ext
10.647 mm
Minor Diameter (D₁) Int
10.827 mm
Thread Height
1.083 mm
Root Radius
0.18 mm
Drilling & Strength Specs
Tap Drill (75%)
10.75 mm
Tap Drill (65%)
10.83 mm
Stress Area
92.07 mm²
Stress Diameter
10.466 mm
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Frequently Asked Questions
What is the tap drill size for a M12x1.25 thread?
For standard thread engagement (approx. 75%), the recommended tap drill size for M12x1.25 is 10.75 mm. For a slightly looser 65% thread engagement, a 10.83 mm drill bit is recommended.
What is the pitch of a M12x1.25 thread?
The thread pitch for a standard M12x1.25 thread is 1.25 mm, which equates to approximately 0.8 threads per millimeter.
What are the major and pitch diameters for M12x1.25?
The nominal major diameter of M12x1.25 is 12 mm. The calculated pitch diameter (d₂) is 11.188 mm per the ISO 68-1/ISO 261 standards.