Dimensions mm · values as the standard states them Size P s k c r a1 dc dp k´ z3 z4 M8 1.25 8
7.78 – 8
11
10.78 – 11.22
2.88 – 3.12
≥ 0.4
≤ 4
10
9.42 – 10
5.5
5.32 – 5.5
≥ 5.5
2 – 2.25
≈ 1
M10 1.5 10
9.78 – 10
13
12.78 – 13.22
2.88 – 3.12
≥ 0.4
≤ 4.5
13
12.3 – 13
7
6.78 – 7
≥ 6.9
2.5 – 2.75
≈ 1
M12 1.75 13
12.73 – 13
16
15.78 – 16.22
3.85 – 4.15
≥ 0.6
≤ 5.3
17
16.3 – 17
8.5
8.28 – 8.5
≥ 8.3
3 – 3.25
≈ 1.25
M16 2 17
16.73 – 17
20
19.74 – 20.26
3.85 – 4.15
≥ 0.6
≤ 6
22
21.16 – 22
12
11.73 – 12
≥ 11.1
4 – 4.3
≈ 1.75
M20 2.5 22
21.67 – 22
25
24.74 – 25.26
4.85 – 5.15
≥ 0.8
≤ 7.5
28
27.16 – 28
15
14.73 – 15
≥ 13.8
5 – 5.3
≈ 2
M24 3 24
23.67 – 24
28
27.74 – 28.26
5.85 – 6.15
≥ 0.8
≤ 9
32
31 – 32
18
17.73 – 18
≥ 15.2
6 – 6.3
≈ 2.5
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.
Length tolerances 16 15.65 – 16.35
20 19.58 – 20.42
25 24.58 – 25.42
30 29.58 – 30.42
35 34.5 – 35.5
40 39.5 – 40.5
50 49.5 – 50.5
60 59.4 – 60.6
70 69.4 – 70.6
80 79.4 – 80.6
90 89.3 – 90.7
100 99.3 – 100.7
110 109.3 – 110.7
120 119.3 – 120.7
140 139.2 – 140.8
Size sheet · DIN 480
M8
s width across flats 8
k head height 11
c thickness of the mounting collar 2.88 – 3.12
r fillet radius ≥ 0.4
a1 length undercut ≤ 4
dc outer diameter of the ring 10
dp diameter of the ejector 5.5
k´ minimum size of the head on the key ≥ 5.5
z3 length of the ejector 2 – 2.25
z4 length of the round end ≈ 1 Thread · ISO 261/262
Pitch P 1.25
d2 7.188
d3 6.466
Tap drill 6.75
Stress area As 36.61 mm² Standard lengths
16 · 20 · 25 · 30 · 35 · 40
Size sheet · DIN 480
M10
s width across flats 10
k head height 13
c thickness of the mounting collar 2.88 – 3.12
r fillet radius ≥ 0.4
a1 length undercut ≤ 4.5
dc outer diameter of the ring 13
dp diameter of the ejector 7
k´ minimum size of the head on the key ≥ 6.9
z3 length of the ejector 2.5 – 2.75
z4 length of the round end ≈ 1 Thread · ISO 261/262
Pitch P 1.5
d2 9.026
d3 8.16
Tap drill 8.5
Stress area As 57.99 mm² Standard lengths
20 · 25 · 30 · 35 · 40 · 50 · 60
Size sheet · DIN 480
M12
s width across flats 13
k head height 16
c thickness of the mounting collar 3.85 – 4.15
r fillet radius ≥ 0.6
a1 length undercut ≤ 5.3
dc outer diameter of the ring 17
dp diameter of the ejector 8.5
k´ minimum size of the head on the key ≥ 8.3
z3 length of the ejector 3 – 3.25
z4 length of the round end ≈ 1.25 Thread · ISO 261/262
Pitch P 1.75
d2 10.863
d3 9.853
Tap drill 10.25
Stress area As 84.27 mm² Standard lengths
25 · 30 · 35 · 40 · 50 · 60
Size sheet · DIN 480
M16
s width across flats 17
k head height 20
c thickness of the mounting collar 3.85 – 4.15
r fillet radius ≥ 0.6
a1 length undercut ≤ 6
dc outer diameter of the ring 22
dp diameter of the ejector 12
k´ minimum size of the head on the key ≥ 11.1
z3 length of the ejector 4 – 4.3
z4 length of the round end ≈ 1.75 Thread · ISO 261/262
Pitch P 2
d2 14.701
d3 13.546
Tap drill 14
Stress area As 156.67 mm² Standard lengths
40 · 50 · 60 · 70 · 80
Size sheet · DIN 480
M20
s width across flats 22
k head height 25
c thickness of the mounting collar 4.85 – 5.15
r fillet radius ≥ 0.8
a1 length undercut ≤ 7.5
dc outer diameter of the ring 28
dp diameter of the ejector 15
k´ minimum size of the head on the key ≥ 13.8
z3 length of the ejector 5 – 5.3
z4 length of the round end ≈ 2 Thread · ISO 261/262
Pitch P 2.5
d2 18.376
d3 16.933
Tap drill 17.5
Stress area As 244.79 mm² Standard lengths
60 · 70 · 80 · 90 · 100 · 110 · 120
Size sheet · DIN 480
M24
s width across flats 24
k head height 28
c thickness of the mounting collar 5.85 – 6.15
r fillet radius ≥ 0.8
a1 length undercut ≤ 9
dc outer diameter of the ring 32
dp diameter of the ejector 18
k´ minimum size of the head on the key ≥ 15.2
z3 length of the ejector 6 – 6.3
z4 length of the round end ≈ 2.5 Thread · ISO 261/262
Pitch P 3
d2 22.051
d3 20.319
Tap drill 21
Stress area As 352.5 mm² Standard lengths
60 · 70 · 80 · 90 · 100 · 110 · 120 · 140
Provenance
Draft — values taken from a single source and not yet cross-checked.
fasteners.eu dimensions, lengths, materials, property classes, current norm, equivalent norms Accessed 2026-09-23 · For design and safety-critical use, consult the current edition of the standard.