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Standard Metric Hex Nuts per ANSI/ASME B18.2.4.1M and B18.2.4.2M
Metric ISO Hardware Engineering Data
Inch ANSI Hardware Engineering Data
Fastener and Screw / Bolt Design, Formula & Calculations
Width Across Metric Nut Flats
The width across flats of nut shall be the distance measured, perpendicular to the axis of nut, overall between two opposite sides of the nut in accordance with the notes on respective dimensional tables. For milled- from-bar hex nuts, the nominal bar size used shall be the closest commercially available size to the specified basic width across flats of the nut. For milled-from- bar nonferrous nuts, the tabulated maximum (basic) width acrws flats dimensions may be exceeded to con- form with the commercial tolerances of drawn or rolled bar stock material.
Metric Nut Thickness
The nut thickness shall be the overall distance, measured parallel to the axis of nut, from the top of the nut to the bearing surface and shall include the thickness of the washer face where provided
Standard Metric Hex Nuts, Types Styles 1 and 2 per.
ANSI/ASME B18.2.4.1M and B18.2.4.2M
All dimensions are in millimeters.
Nominal Nut Dia.
x Thread Pitch |
Width Across
Flats, S |
Width Across
Corners, E |
Thickness
M |
Bearing Face
Dia. Dw |
Washer Face Thickness
C |
||||
---|---|---|---|---|---|---|---|---|---|
Max
|
Min
|
Max
|
Min
|
Max
|
Min
|
Min
|
Max
|
Min
|
|
Metric Hex Nuts — Style 1
|
|||||||||
M1.6 × 0.35
|
3.20
|
3.02
|
3.70
|
3.41
|
1.30
|
1.05
|
2.3
|
…
|
…
|
M2 × 0.4
|
4.00
|
3.82
|
4.62
|
4.32
|
1.60
|
1.35
|
3.1
|
…
|
…
|
M2.5 × 0.45
|
5.00
|
4.82
|
5.77
|
5.45
|
2.00
|
1.75
|
4.1
|
…
|
…
|
M3 × 0.5
|
5.50
|
5.32
|
6.35
|
6.01
|
2.40
|
2.15
|
4.6
|
…
|
…
|
M3.5 × 0.6
|
6.00
|
5.82
|
6.93
|
6.58
|
2.80
|
2.55
|
5.1
|
…
|
…
|
M4 × 0.7
|
7.00
|
6.78
|
8.08
|
7.66
|
3.20
|
2.90
|
6.0
|
…
|
…
|
M5 × 0.8
|
8.00
|
7.78
|
9.24
|
8.79
|
4.70
|
4.40
|
7.0
|
…
|
…
|
M6 × 1
|
10.00
|
9.78
|
11.55
|
11.05
|
5.20
|
4.90
|
8.9
|
…
|
…
|
M8 × 1.25
|
13.00
|
12.73
|
15.01
|
14.38
|
6.80
|
6.44
|
11.6
|
…
|
…
|
a M10 × 1.5
|
15.00
|
14.73
|
17.32
|
16.64
|
9.1
|
8.7
|
13.6
|
0.6
|
0.3
|
M10 × 1.5
|
16.00
|
15.73
|
18.48
|
17.77
|
8.40
|
8.04
|
14.6
|
…
|
…
|
M12 × 1.75
|
18.00
|
17.73
|
20.78
|
20.03
|
10.80
|
10.37
|
16.6
|
…
|
…
|
M14 × 2
|
21.00
|
20.67
|
24.25
|
23.36
|
12.80
|
12.10
|
19.4
|
…
|
…
|
M16 × 2
|
24.00
|
23.67
|
27.71
|
26.75
|
14.80
|
14.10
|
22.4
|
…
|
…
|
M20 × 2.5
|
30.00
|
29.16
|
34.64
|
32.95
|
18.00
|
16.90
|
27.9
|
0.8
|
0.4
|
M24 × 3
|
36.00
|
35.00
|
41.57
|
39.55
|
21.50
|
20.20
|
32.5
|
0.8
|
0.4
|
M30 × 3.5
|
46.00
|
45.00
|
53.12
|
50.85
|
25.60
|
24.30
|
42.5
|
0.8
|
0.4
|
M36 × 4
|
55.00
|
53.80
|
63.51
|
60.79
|
31.00
|
29.40
|
50.8
|
0.8
|
0.4
|
Metric Hex Nuts — Style 2
|
|||||||||
M3 × 0.5
|
5.50
|
5.32
|
6.35
|
6.01
|
2.90
|
2.65
|
4.6
|
…
|
…
|
M3.5 × 0.6
|
6.00
|
5.82
|
6.93
|
6.58
|
3.30
|
3.00
|
5.1
|
…
|
…
|
M4 × 0.7
|
7.00
|
6.78
|
8.08
|
7.66
|
3.80
|
3.50
|
5.9
|
…
|
…
|
M5 × 0.8
|
8.00
|
7.78
|
9.24
|
8.79
|
5.10
|
4.80
|
6.9
|
…
|
…
|
M6 × 1
|
10.00
|
9.78
|
11.55
|
11.05
|
5.70
|
5.40
|
8.9
|
…
|
…
|
M8 × 1.25
|
13.00
|
12.73
|
15.01
|
14.38
|
7.50
|
7.14
|
11.6
|
…
|
…
|
a M10 × 1.5
|
15.00
|
14.73
|
17.32
|
16.64
|
10.0
|
9.6
|
13.6
|
0.6
|
0.3
|
M10 × 1.5
|
16.00
|
15.73
|
18.48
|
17.77
|
9.30
|
8.94
|
14.6
|
…
|
…
|
M12 × 1.75
|
18.00
|
17.73
|
20.78
|
20.03
|
12.00
|
11.57
|
16.6
|
…
|
…
|
M14 × 2
|
21.00
|
20.67
|
24.25
|
23.35
|
14.10
|
13.40
|
19.6
|
…
|
…
|
M16 × 2
|
24.00
|
23.67
|
27.71
|
26.75
|
16.40
|
15.70
|
22.5
|
…
|
…
|
M20 × 2.5
|
30.00
|
29.16
|
34.64
|
32.95
|
20.30
|
19.00
|
27.7
|
0.8
|
0.4
|
M24 × 3
|
36.00
|
35.00
|
41.57
|
39.55
|
23.90
|
22.60
|
33.2
|
0.8
|
0.4
|
M30 × 3.5
|
46.00
|
45.00
|
53.12
|
50.85
|
28.60
|
27.30
|
42.7
|
0.8
|
0.4
|
M36 × 4
|
55.00
|
53.80
|
63.51
|
60.79
|
34.70
|
33.10
|
51.1
|
0.8
|
0.4
|
a Non standard width across flats of 15 mm. This is a special order/size.
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