FRACTION & MACHINE SCREW TAP DRILL SIZES - Based on Approximately 75% Full Thread

Oct 12, 2026

Uploaded by Đào

Fraction & machine screw tap drill sizes chart based on approximately 75% full thread engagement. Provides recommended drill sizes for national coarse and fine thread taps across multiple thread counts, including taper pipe and straight pipe applications. Also includes a metric tap drill sizing table listing metric nominal size and pitch, tap limit numbers, and recommended tap drills with corresponding inch and metric drill diameters, enabling accurate selection for tapping operations.

LanguageEnglish

CategoryGeneral

FormatPDF

Pages1

AccessFree to download

Tap drill sizes tables

National coarse and fine threads (taper pipe, straight pipe)

Metric tap drill sizes (nominal size and pitch)

FRACTION & MACHINE SCREW TAP DRILL SIZES BASED ON APPROXIMATELY 75% FULL THREAD | NATIONAL COARSE & FINE THREADS | | | | TAPER PIPE | | STRAIGHT PIPE | | | --- | --- | --- | --- | --- | --- | --- | --- | | THREAD | DRILL | THREAD | DRILL | THREAD | DRILL | THREAD | DRILL | | \#0—80
\#1—64
\#1—72
\#2—56
\#2—64
\#3—48
\#3—56
\#4—40
\#4—48
\#5—40
\#5—44
\#6—32
\#6—40
\#8—32
\#8—36
\#10—24
\#10—32
\#12—24
\#12—28
1/4—20
1/4—28
5/16—18
5/16—24
3/8—16
3/8—24
7/16—14
7/16—20 | 3/64
NO. 53
NO. 53
NO. 51
NO. 50
5/64
NO. 46
NO. 43
NO. 42
NO. 39
NO. 37
NO. 36
NO. 33
NO. 29
NO. 29
NO. 25
NO. 21
NO. 17
NO. 15
NO. 7
NO. 3
F
I
5/16
Q
U
W | 1/2—13
1/2—20
9/16—12
9/16—18
5/8—11
5/8—18
3/4—10
3/4—16
7/8—9
7/8—14
1—8
1—12
1-1/8—7
1-1/8—12
1-1/4—7
1-1/4—12
1-1/2—6
1-1/2—12
1-3/4—5
1-3/4—12
2—4-1/2
2—12
2-1/4—1-1/2
2-1/2—4
2-3/4—4
3—4 | 27/64
39/64
31/64
33/64
17/32
37/64
21/32
11/16
49/64
13/16
7/8
29/32
63/64
1-3/64
1-7/64
1-11/64
1-11/32
1-27/64
1-35/64
1-43-64
1-25/32
1-59/64
2-1/32
2-1/4
2-1/2
2-3/4 | 1/8—27
1/4—18
3/8—18
1/2—14
3/4—14
1—11-1/2
1-1/4—11-1/2
1-1/2—11-1/2
2—11-1/2
2-1/2—8
3—8
3-1/2—8
4—8
4-1/2—8
5—8
6—8 | R
7/16
37/64
23/32
59/64
1-5/32
1-1/2
1-47/64
2-7/32
2-5/8
3-1/4
3-3/4
4-1/4
4-3/4
5-9/32
6-11/32 | 1/8—27
1/4—18
3/8—18
1/2—14
3/4—14
1—11-1/2
1-1/4—11-1/2
1-1/2—11-1/2
2—11-1/2
2-1/2—8
3—8
3-1/2—8
4—8
4-1/2—8
5—8
6—8 | S
29/64
19/32
47/64
15/16
1-3/16
1-33/64
1-3/4
2-7/32
2-21/32
3-9/32
3-25/32
4-9/32
4-25/32
5-11/32
6-13/32 | | | | | |
| | | | CALL 800-923-6255 METRIC TAP DRILL SIZES | Metric Nominal
Size & Pitch (mm) | Tap Limit No. | Recommended Tap Drills | | | | | --- | --- | --- | --- | --- | --- | | | | Inch Series | | Metric Series | | | | | Nom. Size | Inch Dia. | Size (mm) | Inch Dia. | | M 1.6 x 0.35 | D3 | — | — | 1.25 | .0492 | | M 2 x 0.4 | D3 | \#52 | .0635 | 1.60 | .0630 | | M 2.5 x 0.45 | D3 | \#45 | .0820 | 2.05 | .0807 | | M 3 x 0.5 | D3 | \#39 | .0995 | 2.50 | .0984 | | M 3.5 x 0.6 | D4 | \#32 | .1160 | 2.90 | .1142 | | M 4 x 0.7 | D4 | \#30 | .1285 | 3.30 | .1299 | | M 5 x 0.8 | D4 | \#19 | .1660 | 4.20 | .1654 | | M 6 x 1 | D5 | \#8 | .1990 | 5.00 | .1968 | | M 8 x 1.25 | D5 | “H” | .2660 | 6.80 | .2677 | | M 10 x 1.5 | D6 | “Q” | .3320 | 8.50 | .3346 | | M 12 x 1.75 | D6 | 13/32 | .4062 | 10.25 | .4035 | | M 14 x 2 | D7 | 15/32 | .4688 | 12.00 | .4724 | | M 16 x 2 | D7 | 35/64 | .5469 | 14.00 | .5512 | | M 20 x 2.5 | D7 | 11/16 | .6875 | 17.50 | .6890 | | M 24 x 3 | D8 | 53/64 | .8281 | 21.00 | .8268 | | M 30 x 3.5 | D9 | 1-3/64 | 1.0469 | 26.50 | 1.0433 | | M 36 x 4 | D9 | 1-1/4 | 1.2500 | 32.00 | 1.2598 |

FAQs

What tap-drill chart basis does the document use?

It specifies drill sizes based on approximately 75% full thread.

Does the chart cover both national and metric tap drill sizes?

Yes. It provides national coarse and fine thread drill size recommendations, plus a separate metric tap drill sizes table.

How can taper pipe and straight pipe selections be distinguished?

The national thread section is separated into taper pipe and straight pipe columns, each with its own thread and drill size pairings.

Oct 12, 2026

Uploaded by Đào