Imperial 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 or free 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 imperial bolts and screws.

Clearance Hole Chart for Imperial Bolts

Size of Screw Clearance Hole Drills
Close Fit Free Fit
No. or Diameter  Decimal Equivalent Drill Size Decimal Equivalent Drill Size Decimal Equivalent
0 0.06 52 0.0635 50 0.07
1 0.073 48 0.076 46 0.081
2 0.086 43 0.089 41 0.096
3 0.099 37 0.104 35 0.11
4 0.112 32 0.116 30 0.1285
5 0.125 30 0.1285 29 0.136
6 0.138 27 0.144 25 0.1495
8 0.164 18 0.1695 16 0.177
10 0.19 9 0.196 7 0.201
12 0.216 2 0.221 1 0.228
14 0.242 D 0.246 F 0.257
1/4 0.25 F 0.257 H 0.266
5/16 0.3125 P 0.323 Q 0.332
3/8 0.375 W 0.386 X 0.397
7/16 0.4375 29/64 0.4531 15/32 0.4687
1/2 0.5 33/64 0.5156 17/32 0.5312

How to read the chart – a 1/4″ bolt with a close fit would have an F (0.257) clearance hole.

Metric clearance hole chart

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