M15 Bolt Size and Thread Specifications

Q: What is the standard pitch for an M15 bolt?

The common coarse pitch for M15 is 1.5 mm. Confirm fine or special pitches on the drawing when replacing fasteners.

Q: What imperial fastener is closest to M15?

5/8-11 (approx.) is a practical imperial reference for M15; always verify against your application.

What is an M15 bolt?

An M15 bolt has 15 mm nominal diameter. Coarse pitch is often 1.5 mm in practice, but you must confirm against the part or drawing.

M15 is non-standard in many ISO coarse series listings; pitch can vary by application. Always match the original specification when replacing fasteners. Spanish reference: perno M15.

Specifications

Specification	Value
Nominal diameter	15 mm
Standard pitch (coarse)	1.5 mm
Tap drill size	13.5 mm
Closest imperial equivalent	5/8-11 (approx.)

Hex head size

Bolt size	Hex head size
M15	24 mm

Common uses

Machine builds and OEM parts lists that explicitly specify M15.

Related tools

Metric to Imperial Screw Converter — compare M15 to common inch threads.
Tap Drill Calculator — tap drill size for M15 and other metric threads.
Thread Identifier Tool — match measured diameter and pitch to a standard.

Related charts

Universal Screw & Bolt Size Chart — metric, imperial, pitch, and tap drill in one view.
Tap Drill Chart — metric tap drill sizes.

FAQ

What is the standard pitch for an M15 bolt?

The common coarse pitch for M15 is 1.5 mm. See drawings for fine or special pitches.

What drill size should be used for tapping M15 threads?

For M15 x 1.5 coarse thread, use approximately a 13.5 mm tap drill. Use our Tap Drill Calculator for other pitches.

What imperial fastener is closest to M15?

5/8-11 (approx.) is a practical reference for comparing M15 to inch hardware; verify fit for your application.

Related guide

Metric vs Imperial Fasteners