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TAP DRILL SIZES
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Recommended
tap drill sizes (for appx. 75% thread) — INCH and METRIC
provided by:
VICTOR MACHINERY EXCHANGE, INC.
56 Bogart Street, Brooklyn, NY 11206-3817
Call Toll Free: 1-800-723-5359
Shop online at www.victornet.com
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INCH
SIZES -
NATIONAL COARSE
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| TAP SIZE |
DRILL SIZE |
| #0-80 |
3/64" |
| #1-64 |
#53 |
| #2-56 |
#51 |
| #3-48 |
5/64" |
| #4-40 |
#43 |
| #5-40 |
#39 |
| #6-32 |
#36 |
| #8-32 |
#29 |
| #10-24 |
#25 |
| #12-24 |
#17 |
| 1/4-20 |
#7 |
| 5/16-18 |
F |
| 3/8-16 |
5/16 |
| 7/16-14 |
U |
| 1/2-13 |
27/64 |
| 9/16-12 |
31/64 |
| 5/8-11 |
17/32 |
| 3/4-10 |
21/32 |
| 7/8-9 |
49/64 |
| 1"-8 |
7/8 |
| 1-1/8-7 |
63/64 |
| 1-1/4-7 |
1-7/64 |
| 1-1/2-6 |
1-11/32 |
| 1-3/4-5 |
1-35/64 |
| 2"-4-1/2 |
1-25/32 |
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INCH
SIZES -
NATIONAL FINE |
| TAP SIZE |
DRILL SIZE |
| #1-72 |
#53 |
| #2-64 |
#50 |
| #3-56 |
#46 |
| #4-48 |
#42 |
| #5-44 |
#37 |
| #6-40 |
#33 |
| #8-36 |
#29 |
| #10-32 |
#21 |
| #12-28 |
#15 |
| 1/4-28 |
#3 |
| 5/16-24 |
I |
| 3/8-24 |
Q |
| 7/16-20 |
W |
| 1/2-20 |
29/64 |
| 9/16-18 |
33/64 |
| 5/8-18 |
37/64 |
| 3/4-16 |
11/16 |
| 7/8-14 |
13/16 |
| 1"-14 |
15/16 |
| 1-1/8-12 |
1-3/64 |
| 1-1/4-12 |
1-11/64 |
| 1-1/2-12 |
1-27/64 |
| 1-3/4-12 |
1-43/64 |
| 2"-12 |
1-59/64 |
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| TAPER
PIPE SIZES - NPT |
| TAP SIZE |
DRILL SIZE |
| 1/8-27 |
R |
| 1/4-18 |
7/16 |
| 3/8-18 |
37/64 |
| 1/2-14 |
23/32 |
| 3/4-14 |
59/64 |
| 1"-11-1/2 |
1-5/32 |
| 1-1/4-11-1/2 |
1-1/2 |
| 1-1/2-11-1/2 |
1-47/64 |
| 2"-11-1/2 |
2-7/32 |
| 2-1/2-8 |
2-5/8 |
| 3"-8 |
3-1/4 |
| 3-1/2-8 |
3-3/4 |
| 4"-8 |
4-1/4 |
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| STRAIGHT
PIPE SIZES - NPS |
| TAP SIZE |
DRILL SIZE |
| 1/8-27 |
S |
| 1/4-18 |
29/64 |
| 3/8-18 |
19/32 |
| 1/2-14 |
47/64 |
| 3/4-14 |
15/16 |
| 1"-11-1/2 |
1-3/16 |
| 1-1/4-11-1/2 |
1-33/64 |
| 1-1/2-11-1/2 |
1-3/4 |
| 2"-11-1/2 |
2-7/32 |
| 2-1/2-8 |
2-21/32 |
| 3"-8 |
3-9/32 |
| 3-1/2-8 |
3-25/32 |
| 4"-8 |
4-9/32 |
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| METRIC
COARSE SIZES |
| TAP SIZE |
DRILL SIZE |
| 1mm x .25 |
.75mm |
| 1.1 x .25 |
.85 |
| 1.2 x .25 |
.95 |
| 1.4 x .3 |
1.1 |
| 1.6 x .35 |
1.25 |
| 1.7 x .35 |
1.35 |
| 1.8 x .35 |
1.45 |
| 2 x .4 |
1.6 |
| 2.2 x .45 |
1.75 |
| 2.5 x .45 |
2.05 |
| 3 x .5 |
2.5 |
| 3.5 x .6 |
2.9 |
| 4 x .7 |
3.3 |
| 4.5 x .75 |
3.75 |
| 5 x .8 |
4.2 |
| 6 x 1 |
5 |
| 7 x 1 |
6 |
| 8 x 1.25 |
6.8 |
| 9 x 1.25 |
7.8 |
| 10 x 1.5 |
8.5 |
| 11 x 1.5 |
9.5 |
| 12 x 1.75 |
10.25 |
| 14 x 2 |
12 |
| 16 x 2 |
14 |
| 18 x 2.5 |
15.5 |
| 20 x 2.5 |
17.5 |
| 22 x 2.5 |
19.5 |
| 24 x 3 |
21 |
| 27 x 3 |
24 |
| 30 x 3.5 |
26.5 |
| 33 x 3.5 |
29.5 |
| 36 x 4 |
32 |
| 39 x 4 |
35 |
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| METRIC
FINE SIZES |
| TAP SIZE |
DRILL SIZE |
| 4 mm x .35 |
3.6mm |
| 4 x .5 |
3.5 |
| 5 x .5 |
4.5 |
| 6 x .5 |
5.5 |
| 6 x .75 |
5.25 |
| 7 x .75 |
6.25 |
| 8 x .5 |
7.5 |
| 8 x .75 |
7.25 |
| 8 x 1 |
7 |
| 9 x 1 |
8 |
| 10 x .75 |
9.25 |
| 10 x 1 |
9 |
| 10 x 1.25 |
8.75 |
| 11 x 1 |
10 |
| 12 x .75 |
11.25 |
| 12 x 1 |
11 |
| 12 x 1.5 |
10.5 |
| 14 x 1 |
13 |
| 14 x 1.25 |
12.8 |
| 14 x 1.5 |
12.5 |
| 16 x 1 |
15 |
| 16 x 1.5 |
14.5 |
| 18 x 1 |
17 |
| 18 x 2 |
16 |
| 20 x 1 |
19 |
| 20 x 1.5 |
18.5 |
| 20 x 2 |
18 |
| 22 x 1 |
21 |
| 22 x 1.5 |
20.5 |
| 22 x 2 |
20 |
| 24 x 1.5 |
22.5 |
| 24 x 2 |
22 |
| 26 x 1.5 |
24.5 |
| 27 x 1.5 |
25.5 |
| 27 x 2 |
25 |
| 28 x 1.5 |
26.5 |
| 30 x 1.5 |
28.5 |
| 30 x 2 |
28 |
| 33 x 2 |
31 |
| 36 x 3 |
33 |
| 39 x 3 |
36 |
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To determine the ideal drill size for appx. 75% thread on inch-sized (imperial) special pitch taps, use the following formula:
Drill Size = (Major Diameter of the tap) - (.975 divided by the number of Threads Per Inch)
For example, to find the ideal drill size needed for a 1/4-32 tap:
Drill Size = (1/4") - (.975 / 32 tpi)
Drill Size = .250" - (.975 / 32)
Drill Size = .250" - .0305"
Drill Size = .2195"
Using a decimal chart to find the closest available drill sizes to our calculated ideal drill size of .2195", we'd select either a 7/32" or #2 drill size.
To determine the proper drill size for a metric tap, subtract the tap's pitch from the tap's diameter. For example: a 42mm x 1.5 tap needs a 40.5mm drill (42 - 1.5 = 40.5)
Follow these links to browse our taps and die selection:
For common National Coarse and National Fine sizes we offer
hand taps,
spiral point taps,
spiral flute taps,and
oversize taps, as well as
round adjustable dies, and
hex rethreading dies.
For making metric right hand threads we supply metric taps and
metric dies.
You can buy individual sizes or tap and die sets.
To make left hand threads, choose
inch size left hand taps and dies or
metric left hand taps and dies.
To make pipe threads use pipe taps and dies.
We carry an extensive stock of
special thread taps and
special thread dies.
To cut square threads we offer
acme taps.
In addition to the many sizes we list, custom taps to your specifications can often be shipped in as little as 24 hours.
Follow this link to order metric drill bits or
inch size jobber length drill bits.
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