Metric Tap Drill Sizes
In general, you can find the tap-drill for any size 60 degree thread, subtract one pitch length from the major diameter.
Formula: Major Dia. minus One Pitch Length equals tap-drill size
English Example for 3/8-16 thread: .375 - .0625 = .3125 tap-drill (5/16)
Metric Example for M6 X 1 thread: 6mm - 1mm = 5mm tap-drill
NOTE: The formula and the following Tap Drill Size Tables are only for cutting taps. Do not use this information for roll taps!
| SCREW SIZE |
DRILL SIZE MM |
% THREAD | NEAREST INCH DRILL |
|
M1.6x.35
|
1.25
|
69%
|
3/64
|
|
M1.8x.35
|
1.45
|
69%
|
#53
|
|
M2x.4
|
1.60
|
69%
|
#52
|
|
M2.5x.45
|
2
|
69%
|
#46
|
|
M3x.5
|
2.50
|
68%
|
#40
|
|
M3.5x.6
|
2.90
|
68%
|
#33
|
|
M4x.7
|
3.30
|
69%
|
#30
|
|
M5x.8
|
4.20
|
69%
|
#19
|
| SCREW SIZE |
DRILL SIZE MM |
% THREAD | NEAREST INCH DRILL |
|
M6x1
|
5.00
|
70%
|
#9
|
|
M7x1
|
6.00
|
70%
|
15/64
|
|
M8x1.25
|
6.70
|
74%
|
17/64
|
|
M8x1
|
7.00
|
69%
|
J
|
|
M10x1.5
|
8.50
|
71%
|
Q
|
|
M10x1.25
|
8.70
|
73%
|
11/32
|
|
M12x1.75
|
10.20
|
74%
|
Y
|
|
M12x1.25
|
1.80
|
67%
|
27/64
|
| SCREW SIZE |
DRILL SIZE MM |
% THREAD | NEAREST INCH DRILL |
|
M14x2
|
12.00
|
72%
|
15/32
|
|
M14x1.5
|
12.50
|
71%
|
31/64
|
|
M16x2
|
14.00
|
72%
|
35/64
|
|
M16x1.5
|
14.50
|
71%
|
37/64
|
| M18x2.5 | 15.50 |
73% |
39/64 |
| M18x1.5 | 16.50 |
70% |
21/32 |
|
M20x2.5
|
17.50
|
73%
|
11/16
|
| M20x1.5 | 18.50 |
70% |
47/64 |
| SCREW SIZE |
DRILL SIZE MM |
% THREAD | NEAREST INCH DRILL |