Recommended Tapping Drill Size

ISO Metric Coarse

Size (mm) Pitch (mm) Drill (mm)
M1 .25 .75
M1.1 .25 .85
M1.2 .25 .95
M1.4 .3 1.1
M1.6 .35 1.25
M1.8 .35 1.45
M2 .4 1.6
M2.2 .45 1.75
M2.5 .45 2.05
M3 .5 2.5
M3.5 .6 2.9
M4 .7 3.3
M4.5 .75 3.75
M5 .8 4.2
M6 1 5
M7 1 6
M8 1.25 6.75
M9 1.25 7.75
M10 1.5 8.5
M11 1.5 9.5
M12 1.75 10.2
M14 2 12
M16 2 14
M18 2.5 15.5
M20 2.5 17.5
M22 2.5 19.5
M24 3 21
M27 3 24
M30 3.5 26.5
M33 3.5 29.5
M36 4 32
M39 4 35
M42 4.5 37.5
M45 4.5 40.5
M48 5 43
M52 5 47
M56 5.5 50.5
M60 5.5 54.5
M64 6 58
M68 6 62
M72 6 66
M76 6 70

BSF

Size No.
or inch
Pitch
TPI
Drill (mm)
3/16 32 5.00
1/4 26 6.60
5/16 22 8.30
3/8 20 9.90
7/16 18 11.60
1/2 16 13.00
9/16 16 14.80
5/8 14 16.40
11/16 14 17.70
3/4 12 19.60
7/8 18 16.25
1″ 10 26.50

BS. Brass

Size No.
or inch
Pitch
TPI
Drill (mm)
1/4 26 6.50
5/16 26 8.10
3/8 26 9.70
7/16 26 11.30
1/2 26 12.90

ISO Metric Fine

Size (mm) Pitch (mm) Drill (mm)
M2 .25 1.75
M2.2 .25 1.95
M2.3 .25 2.05
M2.5 .35 2.15
M2.6 .35 2.25
M3 .35 2.65
M3.5 .35 3.15
M4 .35 3.65
M4 .5 3.5
M5 .35 4.65
M5 .5 4.5
M5 .75 4.25
M5.5 .5 5
M6 .5 5.5
M6 .75 5.25
M7 .75 6.25
M8 .5 7.5
M8 .75 7.25
M8 1 7
M9 .75 8.25
M9 1 8
M10 .5 9.5
M10 .75 9.25
M10 1 9
M10 1.25 8.75
M11 .75 10.25
M11 1 10
M11 1.25 9.75
M12 .5 11.5
M12 .75 11.25
M12 1 11
M12 1.25 10.75
M12 1.5 10.5
M14 1 13
M14 1.25 12.75
M14 1.5 12.5
M15 .75 14.25
M15 1 14
M15 1.5 13.5
M16 .5 15.5
M16 .75 15.25
M16 1 15
M16 1.25 14.75
M16 1.5 14.5
M17 1 16
M17 1.5 15.5
M18 .75 17.25
M18 1 17
M18 1.25 16.75
M18 1.5 16.5
M18 2 16
M19 1 18
M20 1 19
M20 1.5 18.5
M20 2 18
M22 1 21
M22 1.5 20.5
M22 2 20
M24 1 23
M24 1.5 22.5
M24 2 22
M25 1 24
M25 1.5 23.5
M25 2 23
M27 1 26
M27 1.5 25.5
M27 2 25
M28 1 27
M28 1.5 26.5
M28 2 26
M30 1 29
M30 1.5 28.5
M30 2 28
M30 3 27
M32 1 31
M32 1.5 30.5
M32 2 30
M33 1.5 31.5
M33 2 31
M33 3 30
M35 1.5 33.5
M35 2 33
M35 3 32
M36 1 35
M36 1.5 34.4
M36 2 34
M36 3 33
M38 1 37
M38 1.5 36.5
M38 2 36
M39 1.5 37.5
M39 2 37
M39 3 36
M40 1 39
M40 1.5 38.5
M40 3 37
M42 1.5 40.5
M42 2 40
M42 3 39
M42 4 38
M45 1.5 43.5
M45 2 43
M45 3 42
M48 1.5 46.5
M48 2 46
M48 3 45
M48 4 44
M50 1.5 48.5
M50 2 48
M50 3 47
M52 1.5 50.5
M52 2 50
M52 3 49
M52 4 48
M56 2 54
M56 4 52

UNC

Size No.
or inch
Pitch
TPI
Drill (mm)
#1 64 1.55
#2 56 1.85
#3 48 2.1
#4 40 2.35
#5 40 2.65
#6 32 2.85
#8 32 3.5
#10 24 3.9
#12 24 4.5
1/4 20 5.1
5/16 18 6.6
3/8 16 8
7/16 14 9.4
1/2 13 10.8
9/16 12 12.2
5/8 11 13.5
3/4 10 16.5
7/8 9 19.5
1 8 22.25
1 1/8 7 25
1 1/4 7 28
1 3/8 6 30.75
1 1/2 6 34
1 3/4 5 39.5
2 4.5 45
2 1/4 4.5 51.5
2 1/2 4 57.25
2 3/4 4 63.5
3 4 70

G (BSP)

Size No.
or inch
Pitch
TPI
Drill (mm)
1/8 26 10.00
1/4 19 13.60
3/8 19 17.10
1/2 14 21.50
5/8 14 23.40
3/4 14 27.00
7/8 14 30.60
1″ 11 33.70

UNx8

Size No.
or inch
Pitch
TPI
Drill (mm)
1 1/8 8 28.75
1 1/4 8 31.75
1 3/8 8 35.00
1 1/2 8 38.00
1 5/8 8 41.50
1 3/4 8 44.50
1 7/8 8 47.75
2″ 8 50.90

UNF

Size No.
or inch
Pitch
TPI
Drill (mm)
#0 80 1.25
#1 72 1.55
#2 64 1.9
#3 56 2.15
#4 48 2.4
#5 44 2.7
#6 40 2.95
#8 36 3.5
#10 32 4.1
#12 28 4.7
1/4 28 5.5
5/16 24 6.9
3/8 24 8.5
7/16 20 9.9
1/2 20 11.5
9/16 18 12.9
5/8 18 14.5
3/4 16 17.5
7/8 14 20.4
1 12 23.25
1 1/8 12 26.5
1 1/4 12 29.5
1 3/8 12 32.75
1 1/2 12 36

BA

Size No.
or inch
Pitch
TPI
Drill (mm)
0 25.40 6.20
2 31.35 4.90
4 38.48 3.80
6 47.92 2.90

BSW

Size No.
or inch
Pitch
TPI
Drill (mm)
1/8 40 3.40
3/16 24 5.10
1/4 20 6.70
5/16 18 8.30
3/8 16 9.90
7/16 14 11.60
1/2 12 13.00
9/16 12 14.80
5/8 11 16.70
11/16 11 17.80
3/4 10 20.00
7/8 9 23.00
1″ 8 26.50

All information is strictly informative

// <![CDATA[ (adsbygoogle = window.adsbygoogle || []).push({}); // ]]>