Colin's Mechanical Data Page

# Tapping and Clearance Drilling Table
# Equivalent Drill Sizes

Tapping and Clearance Drilling Table
All dimensions are in mm
Screw sizes denoted, for example, 2-64 NF and 4-40 NC, refer to the American National Fine and American National Coarse thread systems.
Screw sizes denoted, for example, M 1.6, refers to the Metric thread system. Dimensions are given in mm.

Screw Size Pan head Ordinary Nut Crinkle Washer Flat Washer Tapping Hole Dia.
±   0.05
  0
Clearance Hole Dia.
±   0.12
  0
Dia. Height Across Flats Across Corners Thickness Outside Dia. Thickness Outside Dia. Thickness
2-64 NF
(0.073)		 0.167 0.053 0.187 0.217 0.066 0.211 0.0065 - - 1.80 2.38
4-40 NC
(0.112)		 0.219 0.068 0.250 0.289 0.105 0.255 0.0065 0.220 0.018 2.30 3.00
6-32 NC
(0.138)		 0.270 0.082 0.312 0.361 0.125 0.305 0.009 0.295 0.018 2.80 3.70
8-32 NC
(0.164)		 0.322 0.096 0.344 0.397 0.155 0.345 0.0116 0.365 0.018 3.50 4.40
10-32 NF
(0.190)		 0.373 0.110 0.375 0.433 0.167 0.380 0.0132 0.400 0.018 3.90 5.00
M 1.6 3.20 0.96 3.20 3.70 1.30 3.70 0.16 4.00 0.40 1.25 2.00
M 2 4.00 1.20 4.00 4.60 1.60 4.60 0.16 5.00 0.40 1.60 2.35
M 2.5 5.00 1.50 5.00 5.80 2.00 5.80 0.16 6.50 0.60 2.00 2.95
M 3 6.00 1.80 5.50 6.40 2.40 6.40 0.16 7.00 0.60 2.50 3.36
M 4 8.00 2.40 7.00 8.10 3.20 8.10 0.28 9.00 0.90 3.30 4.40
M 5 10.00 3.00 8.00 9.20 4.00 9.20 0.30 10.00 1.10 4.20 5.40
M 6 12.00 3.60 10.00 11.50 5.00 11.50 0.40 12.50 1.80 5.00 6.40
M 8 16.00 4.80 13.00 15.00 6.50 15.00 0.40 17.00 1.80 6.80 8.40
M 10 20.00 6.00 17.00 19.60 8.00 19.60 0.55 21.00 2.2 8.50 10.40

Tapping and Clearance Drills for Number Machine Screws

Tapping and Clearance Drills for Metric Machine Screws

Tapping and Clearance Drills for Fractional Machine Screws

Equivalent Drill Sizes
"Number" and "Letter" drills to Metric, and Metric to Imperial (B.S. 328 Pt. 1 1959)

Numbered Drills Numbered Drills Lettered Drills Metric Drills with no Imperial Equivalent
Drill
No.		 Imperial
Size
(Inches)		 Metric
Size
(mm)
1 0.228 5.80
2 0.221 5.60
3 0.213 5.40
4 0.209 5.30
5 0.2055 5.20
6 0.204 5.20
7 0.201 5.10
8 0.199 5.10
9 0.196 5.00
10 0.1935 4.90
11 0.191 4.90
12 0.189 4.80
13 0.185 4.70
14 0.182 4.60
15 0.180 4.60
16 0.177 4.50
17 0.173 4.40
18 0.1695 4.30
19 0.166 4.20
20 0.161 4.10
21 0.159 4.00
22 0.157 4.00
23 0.154 3.90
24 0.152 3.90
25 0.1495 3.80
26 0.147 3.70
27 0.144 3.70
28 0.1405 (9/64)  
29 0.136 3.50
30 0.1285 3.30
31 0.120 3.00
32 0.116 2.95
33 0.113 2.85
34 0.111 2.80
35 0.110 2.80
36 0.1065 2.70
37 0.104 2.65
38 0.1015 2.60
39 0.0995 2.55
40 0.098 2.50
41 0.096 2.45
42 0.0935 (3/32)  
43 0.089 2.25
Drill
No.		 Imperial
Size
(Inches)		 Metric
Size
(mm)
44 0.086 2.20
45 0.082 2.10
46 0.081 2.05
47 0.0785 2.00
48 0.075 1.95
49 0.073 1.85
50 0.070 1.80
51 0.067 1.70
52 0.0635 1.60
53 0.0595 1.50
54 0.055 1.40
55 0.052 1.30
56 0.0469 (3/64)  
57 0.043 1.10
58 0.042 1.05
59 0.041 1.05
60 0.040 1.00
61 0.039 1.00
62 0.038 0.98
63 0.037 0.95
64 0.036 0.92
65 0.035 0.90
66 0.033 0.85
67 0.032 0.82
68 0.031 (1/32)  
69 0.0292 0.75
70 0.028 0.70
71 0.026 0.65
72 0.025 0.65
73 0.024 0.60
74 0.0225 0.58
75 0.021 0.52
76 0.020 0.50
77 0.018 0.45
78 0.016 0.40
79 0.0145 0.38
80 0.0135 0.35
     
     
     
     
     
     
Drill
No.		 Imperial
Size
(Inches)		 Metric
Size
(mm)
A 0.234 (15/64)  
B 0.238 6.00
C 0.242 6.10
D 0.246 6.20
E 0.250 (1/4)  
F 0.257 6.50
G 0.261 6.60
H 0.266 (17/64)  
  0.2677 6.80
I 0.272 6.90
J 0.277 7.00
  0.2795 7.10
K 0.281 (9/32)  
  0.2835 7.20
  0.2874 7.30
L 0.290 7.40
M 0.295 7.50
  0.2992 7.60
N 0.302 7.70
O 0.316 8.00
P 0.323 8.20
Q 0.332 8.40
R 0.339 8.60
S 0.348 8.80
  0.3543 9.00
T 0.358 9.10
U 0.368 9.30
V 0.377 (3/8)  
W 0.386 9.80
X 0.397 10.1
Y 0.404 10.3
Z 0.413 10.5
     
     
     
     
     
     
     
     
     
     
     
Metric
Size
(mm)		 Imperial
Size
(Inches)
9.50 0.3740
10.80 0.4250
11.00 0.4331
11.30 0.4449
11.50 0.4528
12.50 0.4921
14.00 0.5512
14.25 0.5610
14.50 0.5709
15.00 0.5906
15.25 0.6004
15.50 0.6102
15.75 0.6201
16.00 0.6299
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
   

Data not guaranteed free from error.

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