M16 Bolt Size and Thread Specifications
Quick answer
M16 bolts use 16mm major diameter with 2.0mm coarse pitch and a 14.0mm tap drill.
They are standard for heavy machinery, structures, and high-load joints.
Use the chart below and metric to imperial conversion when inch equivalents must match stock.
M16 is widely used in structural steel, large machinery, and heavy flanges where high preload and durable threads are required. Spanish reference: perno M16. For tap drill size, thread types, and thread identifier workflows, pair this page with tools as you verify threads.
Specifications
| Specification | Value |
|---|---|
| Nominal diameter | 16 mm |
| Standard pitch (coarse) | 2.0 mm |
| Fine pitch | 1.5 mm |
| Tap drill size | 14.0 mm |
| Closest imperial equivalent | 5/8-11 |
Hex head size
| Bolt size | Hex head size |
|---|---|
| M16 | 24 mm |
Common uses
Steel construction, machine tools, large flanges, and heavy-duty mechanical joints. Cross-check loads with the bolt size chart and screw size conversion when you mix metric and inch bins.
Related tools
Related charts
M16 vs M18 bolt size
Shank diameter and pitch set tap drill, hex key, and strength for each ISO size. Compare values in the tables above with the M18 bolt size page when you resize hardware.
Use the bolt size chart when you compare hex and shank columns across sizes.
Metric vs UNC thread size
Metric threads list diameter in millimeters and pitch in millimeters per thread; UNC lists nominal inch diameter and threads per inch. They are not interchangeable—taps, dies, and gauges differ.
Read metric vs unc thread context when series labels are unclear.
Use screw size conversion when you must match stocked parts.
M16 specifications and tools
How to choose the right bolt size
Choosing the correct bolt size depends on load, material, and thread type. Larger diameters increase strength, while thread pitch affects holding force.
Use the bolt size chart to compare shank and hex dimensions before you standardize hardware.
Use tap drill size guidance when you plan tapped holes.
Use the thread identifier when stamped sizes are missing.
FAQ
What is the standard pitch for an M16 bolt?
The common coarse pitch for M16 is 2.0 mm. Fine pitch is often 1.5 mm where specified.
What drill size should be used for tapping M16 threads?
For M16 x 2.0 coarse thread, use approximately a 14.0 mm tap drill. Use our Tap Drill Calculator for other pitches.
What imperial fastener is closest to M16?
5/8-11 is a practical reference for comparing M16 to inch hardware; verify fit for your application.