Counter-bored holes

Counterbore diameter, depth, countersink, and clearance dimensions for USA and metric socket-head cap screws.

Counter-bored holes
Screw dia Counterbore dia (A) Counterbore depth (B) Countersink dia (C) Clearance dia (D)
Normal fit Close fit
USA socket-head cap screws
#0 1/8 .060 .074 #49 #51
#2 3/16 .086 .102 #36 3/32
#4 7/32 .112 .130 #29 1/8
#5 1/4 .125 .145 #23 9/64
#6 9/32 .138 .158 #18 #23
#8 5/16 .164 .188 #10 #15
#10 3/8 .190 .218 #2 #5
1/4 7/16 .250 .278 9/32 17/64
5/16 17/32 .312 .346 11/32 21/64
3/8 5/8 .375 .415 13/32 25/64
7/16 23/32 .438 .483 15/32 29/64
1/2 13/16 .500 .552 17/32 33/64
5/8 1 .625 .689 21/32 41/64
3/4 1-3/16 .750 .828 25/32 49/64
7/8 1-3/8 .875 .963 29/32 57/64
1 1-5/8 1.000 1.100 1-1/32 1-1/64
1-1/4 2 1.250 1.370 1-5/16 1-9/32
1-1/2 2-3/8 1.500 1.640 1-9/16 1-17/32
1-3/4 2-3/4 1.750 1.910 1-13/16 1-25/32
2 3-1/8 2.000 2.180 2-1/16 2-1/32
Metric socket-head cap screws
M1.6 3.50 mm 1.6 mm 2.0 mm 1.95 mm 1.80 mm
M2 4.40 mm 2 mm 2.6 mm 2.40 mm 2.20 mm
M2.5 5.40 mm 2.5 mm 3.1 mm 3.00 mm 2.70 mm
M3 6.50 mm 3 mm 3.6 mm 3.70 mm 3.40 mm
M4 8.25 mm 4 mm 4.7 mm 4.80 mm 4.40 mm
M5 9.75 mm 5 mm 5.7 mm 5.80 mm 5.40 mm
M6 11.20 mm 6 mm 6.8 mm 6.80 mm 6.40 mm
M8 14.50 mm 8 mm 9.2 mm 8.80 mm 8.40 mm
M10 17.50 mm 10 mm 11.2 mm 10.80 mm 10.50 mm
M12 19.50 mm 12 mm 14.2 mm 13.00 mm 12.50 mm
M14 22.50 mm 14 mm 16.2 mm 15.00 mm 14.50 mm
M16 25.50 mm 16 mm 18.2 mm 17.00 mm 16.50 mm
M20 31.50 mm 20 mm 22.4 mm 21.00 mm 20.50 mm
M24 37.50 mm 24 mm 26.4 mm 25.00 mm 24.50 mm
M30 47.50 mm 30 mm 33.4 mm 31.50 mm 31.00 mm
M36 56.50 mm 36 mm 39.4 mm 37.50 mm 37.00 mm
M42 66.00 mm 42 mm 45.6 mm 44.00 mm 43.00 mm
M48 75.00 mm 48 mm 52.6 mm 50.00 mm 49.00 mm