To Tap This Size Screw Or Bolt:
|
Use This Drill Bit:
|
(Closest Fractional:)
|
Decimal Inches
|
0-80 NF
|
3/64"
|
3/64"
|
.0469
|
1-64 NC
|
#53
|
-
|
.0595
|
1-72 NF
|
#53
|
1/16"
|
.0595
|
2-56 NC
|
#50
|
-
|
.0700
|
2-64 NF
|
#50
|
-
|
.0700
|
3-48 NC
|
#47
|
5/64"
|
.0785
|
3-56 NF
|
#45
|
-
|
.0820
|
4-36 NS
|
#44
|
-
|
.0860
|
4-40 NC
|
#43
|
3/32"
|
.0890
|
4-48 NF
|
#42
|
3/32"
|
.0935
|
3mm-0.60mm
|
2.5mm
|
-
|
.0984
|
1/8-40 NS
|
#38
|
-
|
.1015
|
5-40 NC
|
#38
|
-
|
.1015
|
5-44 NF
|
#37
|
-
|
.1040
|
6-32 NC
|
#35
|
7/64"
|
.1100
|
6-36 NS
|
#34
|
-
|
.1110
|
6-40 NF
|
#33
|
-
|
.1130
|
6-48 NS
|
#31
|
-
|
.1200
|
4mm-0.70mm
|
3.4mm
|
-
|
.1338
|
4mm-0.75mm
|
3.4mm
|
-
|
.1338
|
8-32 NC
|
#29
|
-
|
.1360
|
8-36 NF
|
#29
|
9/64"
|
.1360
|
8-40 NS
|
#28
|
-
|
.1405
|
3/16-24 NS
|
#26
|
-
|
.1470
|
10-24 NC
|
#25
|
5/32"
|
.1495
|
3/16-32 NS
|
#22
|
-
|
.1570
|
10-32 NF
|
#21
|
5/32"
|
.1590
|
5mm-0.90mm
|
4.2mm
|
-
|
.1653
|
5mm-0.80mm
|
4.3mm
|
-
|
.1693
|
12-24 NC
|
#16
|
11/64"
|
.1770
|
12-28 NF
|
#14
|
3/16"
|
.1820
|
12-32 NEF
|
#13
|
-
|
.1850
|
14-20 NS
|
#10
|
-
|
.1935
|
1/4-20 NC
|
#7
|
13/64"
|
.2010
|
14-24 NS
|
#7
|
-
|
.2010
|
6mm-1.00mm
|
5.2mm
|
-
|
.2047
|
1/4-24 NS
|
#4
|
-
|
.2090
|
1/4-28 NF
|
#3
|
7/32"
|
.2130
|
1/4-32 NEF
|
7/32"
|
7/32"
|
.2188
|
1/4-40 NS
|
#1
|
-
|
.2280
|
7mm-1.00mm
|
6.1mm
|
15/64"
|
.2401
|
5/16-18 NC
|
Ltr.F
|
17/64"
|
.2570
|
8mm-1.25mm
|
6.9mm
|
17/64"
|
.2716
|
5/16-24 NF
|
Ltr.I
|
-
|
.2720
|
8mm-1.00mm
|
7.1mm
|
-
|
.2795
|
5/16-32 NEF
|
9/32"
|
9/32"
|
.2812
|
9mm-1.25mm
|
7.9mm
|
-
|
.3110
|
3/8-16 NC
|
5/16"
|
5/16"
|
.3125
|
* These Sizes Are Spark Plug Taps
|
To Tap This Size Screw Or Bolt:
|
Use This Drill Bit:
|
(Closest Fractional:)
|
Decimal Inches
|
9mm-1.00mm
|
8.1mm
|
-
|
.3189
|
9mm-0.75mm
|
8.3mm
|
-
|
.3268
|
3/8-24 NF
|
Ltr.Q
|
21/64"
|
.3320
|
10mm-1.50mm
|
8.7mm
|
-
|
.3425
|
10mm-1.25mm
|
8.9mm
|
11/32"
|
.3503
|
10mm-1.00mm*
|
9.1mm
|
-
|
.3583
|
7/16-14 NC
|
Ltr.U
|
23/64"
|
.3680
|
11mm-1.50mm
|
9.7mm
|
-
|
.3818
|
7/16-20 NF
|
25/64"
|
25/64"
|
.3906
|
12mm-1.75mm
|
10.5mm
|
-
|
.4133
|
12mm-1.50mm
|
10.7mm
|
27/64"
|
.4212
|
1/2-13 NC
|
27/64"
|
27/64"
|
.4219
|
12mm-1.25mm*
|
10.9mm
|
27/64"
|
.4291
|
1/2-20 NF
|
29/64"
|
29/64"
|
.4531
|
1/2-24 NS
|
29/64"
|
29/64"
|
.4531
|
14mm-2.00mm
|
12.2mm
|
-
|
.4803
|
9/16-12 NC
|
31/64"
|
31/64"
|
.4844
|
14mm-1.50mm
|
12.7mm
|
-
|
.4999
|
14mm-1.25mm*
|
12.8mm
|
-
|
.5039
|
9/16-18 NF
|
33/64"
|
33/64"
|
.5156
|
5/8-11 NC
|
17/32"
|
17/32"
|
.5312
|
16mm-2.00mm
|
14.2mm
|
35/64"
|
.5590
|
5/8-18 NF
|
37/64"
|
37/64"
|
.5781
|
16mm-1.50mm
|
14.7mm
|
-
|
.5787
|
11/16-11 NS
|
19/32"
|
19/32"
|
.5938
|
18mm-2.50mm
|
15.8mm
|
39/64"
|
.6220
|
11/16-16 NS
|
5/8"
|
5/8"
|
.6250
|
3/4-10 NC
|
21/32"
|
21/32"
|
.6562
|
18mm-1.50mm*
|
16.8mm
|
-
|
.6614
|
3/4-16 NF
|
11/16"
|
11/16"
|
.6875
|
20mm-2.50mm
|
17.8mm
|
11/16"
|
.7008
|
7/8-9 NC
|
49/64"
|
49/64"
|
.7656
|
7/8-14 NF
|
13/16"
|
13/16"
|
.8125
|
22mm-1.50mm
|
20.9mm
|
-
|
.8228
|
7/8-18 NS*
|
53/64"
|
53/64"
|
.8281
|
24mm-3.00mm
|
21.4mm
|
53/64"
|
.8425
|
1.8 NC
|
7/8"
|
7/8"
|
.8750
|
24mm-2.00mm
|
22.3mm
|
-
|
.8779
|
1.12 NF
|
59/64"
|
59/64"
|
.9219
|
1-14 NS
|
15/16"
|
15/16"
|
.9375
|
1 1/8-7 NC
|
63/64"
|
63/64"
|
.9844
|
1 1/8-12 NF
|
1 3/64"
|
1 3/64"
|
1.0469
|
1 1/4-7 NC
|
1 7/64"
|
1 7/64"
|
1.1094
|
1 1/4-12 NF
|
1 11/64"
|
1 11/64"
|
1.1719
|
1 3/8-6 NC
|
1 7/32"
|
1 7/32"
|
1.2188
|
1 3/8-12 NF
|
1 19/64"
|
1 19/64"
|
1.2969
|
1 1/2-6 NC
|
1 11/32"
|
1 11/32"
|
1.3438
|
1 1/2"-12 NF
|
1 27/64"
|
1 27/64"
|
1.4219
|
|