Metric Thread Atlas

The Metric Thread Atlas is a searchable static engineering dataset for metric thread designations and workflow decisions.

Metric thread designations use nominal diameter and pitch notation such as M8x1.25.

This atlas consolidates coarse and fine pitch context, hex sizes, tap drill guidance, and clearance-hole references.

Use filters and search below for instant lookup, then continue with related standards and tools.

Data quality

Dataset version: v0.1.0
Verified: Yes
Last reviewed: 2026-07-12
Verification method: Public engineering reference synthesis reviewed for BoltLab atlas use.
Related standards: ISO 261, ISO 262, ISO 724, ISO 965-1

Search designation Diameter Series Pitch ISO family

Designation	Diameter (mm)	Coarse pitch	Fine pitches	Hex (mm)	Tap drill (mm)	Clearance holes C/N/L (mm)	ISO family
M3	3	0.5	-	5.5	2.5	3.2 / 3.4 / 3.6	ISO 261 / ISO 262
M4	4	0.7	-	7	3.3	4.3 / 4.5 / 4.8	ISO 261 / ISO 262
M5	5	0.8	-	8	4.2	5.3 / 5.5 / 5.8	ISO 261 / ISO 262
M6	6	1	-	10	5	6.4 / 6.6 / 7	ISO 261 / ISO 262
M8	8	1.25	1	13	6.8	8.4 / 9 / 10	ISO 261 / ISO 262
M10	10	1.5	1.25	17	8.5	10.5 / 11 / 12	ISO 261 / ISO 262
M12	12	1.75	1.25	19	10.2	13 / 13.5 / 14.5	ISO 261 / ISO 262
M16	16	2	1.5	24	14	17 / 18 / 20	ISO 261 / ISO 262
M20	20	2.5	2	30	17.5	21 / 22 / 24	ISO 261 / ISO 262