Metric Clearance Hole Sizes

A clearance hole is a hole drilled through a component to allow a bolt to pass through. Deciding if the hole should have a close, normal or loose fit depends on the scope of the project. For example, a looser fit simplifies the assembly process and a closer fit allows for tighter tolerances.

Use the table below to determine the clearance hole size for metric bolts.

Clearance Hole Chart for Metric Bolts

Size – Nominal Diameter (mm) Clearance Hole (mm)
Close Fit Normal Fit Loose Fit
1 1.1 1.2 1.3
1.2 1.3 1.4 1.5
1.4 1.5 1.6 1.8
1.6 1.7 1.8 2
1.8  2 2.1  2.2
2 2.2 2.4 2.6
2.2 2.4  2.6  2.8
2.5 2.7 2.8 3.1
3 3.2 3.35 3.6
3.5  3.7 3.9  4.2
4 4.3 4.5 4.8
4.5  4.8 5  5.3
5 5.3 5.5 5.8
6 6.4 6.5 7
7 7.4 7.8 8
8 8.4 9 10
10 10.5 11 12
12 13 14 15
16 17 18 19
20 21 22 24
24 25 26 28
30 31 32 35
30 31 33 35
33 34 36 38
36 37 39 42
39 40 42 45
42 43 45 48
45 46 48 52
48 50 52 56
52 54 56 62
56 58 62 66
60 62 66 70
64 66 70 74
68 70 74 78
72 74 78 82
76 78 82 86
80 82 86 91
85 87 91 96
90 93 96 101
95 98 101 107
100 104 107 112
105 109 112 117
110 114 117 122
115 119 122 127
120 124 127 132
125 129 132 137
130 134 137 144
140 144 147 155
150 155 158 165

How to read the chart – An M8 bolt with a normal fit should have a 9 mm clearance hole.

Imperial clearance hole chart

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