M19 Bolt Size and Thread Specifications
Quick answer
M19 bolts use 19mm major diameter with 2.5mm coarse pitch in typical references.
They are uncommon but appear between M18 and M20 in some designs.
Use the tables below and thread identifier readings when worn threads confuse sizing.
M19 is rare in general hardware; sourcing taps, dies, and mates may require industrial suppliers. Follow OEM documentation. Spanish reference: perno M19. For tap drill size, thread types, and thread identifier workflows, pair this page with tools as you verify threads.
Specifications
| Specification | Value |
|---|---|
| Nominal diameter | 19 mm |
| Standard pitch (coarse) | 2.5 mm |
| Tap drill size | 16.5 mm |
| Closest imperial equivalent | 3/4-10 (approx.) |
Hex head size
| Bolt size | Hex head size |
|---|---|
| M19 | 30 mm |
Common uses
Applications where M19 is specified on original equipment documentation. Cross-check loads with the bolt size chart and screw size conversion when you mix metric and inch bins.
Related tools
Related charts
M19 vs M20 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 M20 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.
M19 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 M19 bolt?
The common coarse pitch for M19 is 2.5 mm. See drawings for fine or special pitches.
What drill size should be used for tapping M19 threads?
For M19 x 2.5 coarse thread, use approximately a 16.5 mm tap drill. Use our Tap Drill Calculator for other pitches.
What imperial fastener is closest to M19?
3/4-10 (approx.) is a practical reference for comparing M19 to inch hardware; verify fit for your application.