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CLEARANCE HOLE CHART
Clearance hole chart for inch bolts and screws according to ASME B18.2.8
Clearance Hole Chart for Inch Fasteners
Nominal Screw Size
Fit Class - Normal
Fit Class - Close
Fit Class - Loose
Nominal Drill Size
Hole Diameter
Nominal Drill Size
Hole Diameter
Nominal Drill Size
Hole Diameter
Min.
Max.
Min.
Max.
Min.
Max.
#0
#48
0.076
0.082
#51
0.067
0.071
3/32
0.094
0.104
#1
#43
0.089
0.095
#46
0.081
0.085
#37
0.104
0.114
#2
#38
0.102
0.108
3/32
0.094
0.098
#32
0.116
0.126
#3
#32
0.116
0.122
#36
0.106
0.110
#30
0.128
0.140
#4
#30
0.128
0.135
#31
0.120
0.124
#27
0.144
0.156
#5
5/32
0.156
0.163
9/64
0.141
0.146
11/64
0.172
0.184
#6
#18
0.170
0.177
#23
0.154
0.159
#13
0.185
0.197
#8
#9
0.196
0.203
#15
0.180
0.185
#3
0.213
0.225
#10
#2
0.221
0.228
#5
0.206
0.211
B
0.238
0.250
1/4
9/32
0.281
0.290
17/64
0.266
0.272
19/64
0.297
0.311
Nominal Screw Size
Fit Class - Normal
Fit Class - Close
Fit Class - Loose
Nominal Drill Size
Hole Diameter
Nominal Drill Size
Hole Diameter
Nominal Drill Size
Hole Diameter
Min.
Max.
Min.
Max.
Min.
Max.
5/16
11/32
0.344
0.354
21/64
0.328
0.334
23/64
0.359
0.373
3/8
13/32
0.406
0.416
25/64
0.391
0.397
27/64
0.422
0.438
7/16
15/32
0.469
0.479
29/64
0.453
0.460
31/64
0.484
0.500
1/2
9/16
0.562
0.572
17/32
0.531
0.538
39/64
0.609
0.625
5/8
11/16
0.688
0.698
21/32
0.656
0.663
47/64
0.734
0.754
3/4
13/16
0.812
0.824
25/32
0.781
0.789
29/32
0.906
0.926
7/8
15/16
0.938
0.950
29/32
0.906
0.914
1-1/32
1.031
1.051
1
1-3/32
1.094
1.106
1-1/32
1.031
1.039
1-5/32
1.156
1.181
Nominal Screw Size
Fit Class - Normal
Fit Class - Close
Fit Class - Loose
Nominal Drill Size
Hole Diameter
Nominal Drill Size
Hole Diameter
Nominal Drill Size
Hole Diameter
Min.
Max.
Min.
Max.
Min.
Max.
1-1/8
1-7/32
1.219
1.235
1-5/32
1.156
1.164
1-5/16
1.312
1.337
1-1/4
1-11/32
1.344
1.360
1-9/32
1.281
1.291
1-7/16
1.438
1.463
1-3/8
1-1/2
1.500
1.516
1-7/16
1.438
1.448
1-39/64
1.609
1.634
1-1/2
1-5/8
1.625
1.641
1-9/16
1.562
1.572
1-47/64
1.734
1.759
Supplements:
Thread calculators and charts
Clearance hole calculator
Reference:
Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) .
Machinery's Handbook
. 30th edition. Industrial Press Inc.
Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2012) .
Machinery's Handbook
. 29th edition. Industrial Press Inc.
ASME B18.2.8-1999, Clearance holes for bolts, screws and studs