Metric Coarse vs Fine Threads
Metric threads are written as diameter x pitch in millimetres. Coarse pitch is the default and is often omitted; a fine pitch must always be written.
Common pitches, mm
| Size | Coarse | Fine |
|---|---|---|
| M6 | 1.0 | 0.75 |
| M8 | 1.25 | 1.0 |
| M10 | 1.5 | 1.25 / 1.0 |
| M12 | 1.75 | 1.25 / 1.5 |
| M14 | 2.0 | 1.5 |
| M16 | 2.0 | 1.5 |
| M20 | 2.5 | 1.5 |
| M24 | 3.0 | 2.0 |
| M30 | 3.5 | 2.0 |
These tables carry the same figures as the printed sheet below.
The printed sheet
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Text version of this sheet
ISO 261 / ISO 262 · metric screw threads · coarse and fine
What it is
FIELD IDENTIFICATION
Metric threads are written as diameter x pitch in millimetres. Coarse pitch is the default and is often
omitted; a fine pitch must always be written.
M10 x 1.5 (coarse)
M10 x 1.25 (fine)
Same diameter, different pitch
Common pitches, mm
Size
Coarse
Fine
M6
1.0
0.75
M8
1.25
1.0
M10
1.5
1.25 / 1.0
M12
1.75
1.25 / 1.5
M14
2.0
1.5
M16
2.0
1.5
M20
2.5
1.5
M24
3.0
2.0
M30
3.5
2.0
Key points
M10 alone means M10 x 1.5. If it is fine thread, it must say M10 x 1.25.
Metric and inch threads of similar size do not mix: M8 x 1.25 is not 5/16-18.
Governing standards: ISO 261; ISO 262; ISO 965. Editions shown are the latest confirmed as of September 2026. The drawing and the governing standard always take precedence
over this sheet.
torquing any fastener. Verify the current governing standard, project documents, OEM requirements, size, thread, coating and lot certification. To the fullest extent permitted by law, The Fastener App disclaims liability
arising from reliance on this reference.
Fastener Guide reference FG-BD66CE · thefastenerapp.com/fastener-guide/technical-reference/metric-coarse-vs-fine-threads · © The Fastener App. Reference only — verify the current governing standard, drawing and manufacturer data before specifying or installing.
