M16 Thread Specs
Standard: ISO 261 (ISO Metric Coarse)
This reference guide outlines the technical dimensions and tapping parameters for the standard M16 metric thread.
Part of the ISO Metric Coarse series defined by ISO 261, the thread features a nominal diameter of 16 mm and a pitch of 2 mm.
For machining or fabrication, the recommended tap drill size is 14 mm (for 75% thread depth) or 14.12 mm (for 65% thread depth).
Dimensional Specifications (mm)
Nominal Diameter
16 mm
Pitch
2 mm
Threads per mm
0.5
Major Diameter
16 mm
Pitch Diameter (d₂)
14.701 mm
Minor Diameter (d₁) Ext
13.835 mm
Minor Diameter (D₁) Int
14.124 mm
Thread Height
1.732 mm
Root Radius
0.289 mm
Drilling & Strength Specs
Tap Drill (75%)
14 mm
Tap Drill (65%)
14.12 mm
Stress Area
156.67 mm²
Stress Diameter
13.546 mm
Recommended Tightening Torque
| Property Class | Dry (Nm) | Lubricated (Nm) |
|---|---|---|
| Class 8.8 | 260 | 195 |
| Class 10.9 | 383 | 287.3 |
| Class 12.9 | 459 | 344.3 |
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Frequently Asked Questions
What is the tap drill size for a M16 thread?
For standard thread engagement (approx. 75%), the recommended tap drill size for M16 is 14 mm. For a slightly looser 65% thread engagement, a 14.12 mm drill bit is recommended.
What is the pitch of a M16 thread?
The thread pitch for a standard M16 thread is 2 mm, which equates to approximately 0.5 threads per millimeter.
What are the major and pitch diameters for M16?
The nominal major diameter of M16 is 16 mm. The calculated pitch diameter (d₂) is 14.701 mm per the ISO 68-1/ISO 261 standards.