Dimensions mm · values as the standard states them Size P dk k b da a t A recess_no hexalobular M2 0.4 ≤ 3.62
≤ 1.55
≥ 25
≤ 2.6
≤ 0.8
≤ 0.84
1.75
6
M2.5 0.45 ≤ 4.32
≤ 1.85
≥ 25
≤ 3.1
≤ 0.9
≤ 0.91
2.4
8
M3 0.5 ≤ 5.32
≤ 2.4
≥ 25
≤ 3.6
≤ 1
≤ 1.27
2.8
10
M4 0.7 ≤ 6.78
≤ 3.1
≥ 38
≤ 4.7
≤ 1.4
≤ 1.66
3.95
20
M5 0.8 ≤ 8.28
≤ 3.65
≥ 38
≤ 5.7
≤ 1.6
≤ 1.91
4.5
25
M6 1 ≤ 9.78
≤ 4.4
≥ 38
≤ 6.8
≤ 2
≤ 2.29
5.6
30
M8 1.25 ≤ 12.73
≤ 5.8
≥ 38
≤ 9.2
≤ 2.5
≤ 3.05
7.95
45
M10 1.5 ≤ 15.73
≤ 6.9
≥ 38
≤ 11.2
≤ 3
≤ 3.43
8.95
50
Ranges read min – max; ≤ / ≥ where the standard gives one limit, ≈ for approximate values. Sizes in (brackets) are non-preferred. Select a row for its size sheet.
Size sheet · ISO 14580
M2
dk head diameter ≤ 3.62
k head height ≤ 1.55
b thread length ≥ 25
da transition diameter ≤ 2.6
a length undercut ≤ 0.8
t groove depth ≤ 0.84
A 1.75
recess_no drive size (hexalobular) 6 Thread · ISO 261/262
Pitch P 0.4
d2 1.74
d3 1.509
Tap drill 1.6
Stress area As 2.07 mm² Size sheet · ISO 14580
M2.5
dk head diameter ≤ 4.32
k head height ≤ 1.85
b thread length ≥ 25
da transition diameter ≤ 3.1
a length undercut ≤ 0.9
t groove depth ≤ 0.91
A 2.4
recess_no drive size (hexalobular) 8 Thread · ISO 261/262
Pitch P 0.45
d2 2.208
d3 1.948
Tap drill 2.05
Stress area As 3.39 mm² Size sheet · ISO 14580
M3
dk head diameter ≤ 5.32
k head height ≤ 2.4
b thread length ≥ 25
da transition diameter ≤ 3.6
a length undercut ≤ 1
t groove depth ≤ 1.27
A 2.8
recess_no drive size (hexalobular) 10 Thread · ISO 261/262
Pitch P 0.5
d2 2.675
d3 2.387
Tap drill 2.5
Stress area As 5.03 mm² Size sheet · ISO 14580
M4
dk head diameter ≤ 6.78
k head height ≤ 3.1
b thread length ≥ 38
da transition diameter ≤ 4.7
a length undercut ≤ 1.4
t groove depth ≤ 1.66
A 3.95
recess_no drive size (hexalobular) 20 Thread · ISO 261/262
Pitch P 0.7
d2 3.545
d3 3.141
Tap drill 3.3
Stress area As 8.78 mm² Size sheet · ISO 14580
M5
dk head diameter ≤ 8.28
k head height ≤ 3.65
b thread length ≥ 38
da transition diameter ≤ 5.7
a length undercut ≤ 1.6
t groove depth ≤ 1.91
A 4.5
recess_no drive size (hexalobular) 25 Thread · ISO 261/262
Pitch P 0.8
d2 4.48
d3 4.019
Tap drill 4.2
Stress area As 14.18 mm² Size sheet · ISO 14580
M6
dk head diameter ≤ 9.78
k head height ≤ 4.4
b thread length ≥ 38
da transition diameter ≤ 6.8
a length undercut ≤ 2
t groove depth ≤ 2.29
A 5.6
recess_no drive size (hexalobular) 30 Thread · ISO 261/262
Pitch P 1
d2 5.35
d3 4.773
Tap drill 5
Stress area As 20.12 mm² Size sheet · ISO 14580
M8
dk head diameter ≤ 12.73
k head height ≤ 5.8
b thread length ≥ 38
da transition diameter ≤ 9.2
a length undercut ≤ 2.5
t groove depth ≤ 3.05
A 7.95
recess_no drive size (hexalobular) 45 Thread · ISO 261/262
Pitch P 1.25
d2 7.188
d3 6.466
Tap drill 6.75
Stress area As 36.61 mm² Size sheet · ISO 14580
M10
dk head diameter ≤ 15.73
k head height ≤ 6.9
b thread length ≥ 38
da transition diameter ≤ 11.2
a length undercut ≤ 3
t groove depth ≤ 3.43
A 8.95
recess_no drive size (hexalobular) 50 Thread · ISO 261/262
Pitch P 1.5
d2 9.026
d3 8.16
Tap drill 8.5
Stress area As 57.99 mm² Provenance
Reviewed — dimensions cross-checked against the official ISO preview; values match.
Accessed 2026-09-23 · For design and safety-critical use, consult the current edition of the standard.
Data notes (1) Dimensions cross-checked against the official ISO 14580:2011 preview — values match.