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Decimal Equivalents and Tap Sizes of Fraction, Number, Letter and Metric Sizes
Recommended tap drill sizes for approximately 75% depth of thread
Click the following link for a drill sizes for special tap sizes 
SIZES
DEC.
INCHES
TAP SIZES
To be used with
drills as indicated
 
SIZES
DEC.
INCHES
TAP SIZES
To be used with
drills as indicated
 SIZES
DEC.
INCHES
TAP SIZES
To be used with
drills as indicated
 SIZES
DEC.
INCHES
TAP SIZES
To be used with
drills as indicated
 SIZES
DEC.
INCHES
TAP SIZES
To be used with
drills as indicated
97 .0059   58 .0420   27 .1440   H .2660   17/32 .5312 5/8-11
.15mm .0059   57 .0430   3.7mm .1457   6.8mm .2677   13.5mm .5315
96 .0063   1.1mm .0433   26 .1470 3/16-24NS   6.9mm .2717   35/64 .5469
.16mm .0063   1.15mm .0453   3.75mm .1476 m4.5x0.75   I 2720 5/16-24 NF   14mm 5512 m16x2
95 .0067   56 .0465   25 .1495 #10-24   7mm .2756 m8x1   9/16 .5625
.17mm .0067   3/64 .0469 #0-80   3.8mm .1496   J .2770   14.5mm .5709 m16x1.50
94 .0071   1.2mm .0472   24 .1520   7.1mm .2795   37/64 .5781 3/8-18  NPT PIPE  5/8-18 NF
.18mm .0071   1.25mm .0492 m1.6x0.35   3.9mm .1535   K .2810   15mm .5906
93 .0075   1.3mm .0512   23 .1540   9/32 .2812 5/16-32 NS   19/32 .5938 3/8-18  NPS PIPE
.19mm .0075   55 .0520   5/32 .1562   7.2mm .2835   39/64 .6094
92 .0079   1.35mm .0531   22 .1570 3/16-32 NS   7.25mm .2854   15.5mm .6102 m18x2.5
.2mm .0079   54 .0550   4mm .1575   7.3mm .2874   5/8 .6250 11/16-16 NS
91 .0083   1.4mm .0551   21 .1590 #10-32   L .2900   16mm .6299 n18x2.0
.21mm .0083   1.45mm .0571 m1.8x0.35   20 .1610   7.4mm .2913   41/64 .6406
90 .0087   1.5mm .0591   4.1mm .1614   M .2950   16.5mm .6496
.22mm .0087   53 .0595 #1-64,72   4.2mm .1654 m5x0.8   7.5mm .2953   21/32 .6562 3/4-10 NC
89 .0091   1.55mm .0610   19 .1660   19/64 .2969   17mm .6693
.23mm .0091   1/16 .0625   4.25mm .1673   7.6mm .2992   43/64 .6719
.24mm .0094   1.6mm .0630 m2x0.4   4.3mm .1693   N .3020   11/16 .6875 3/4-16 NF
88 .0095   52 .0635   18 .1695   7.7mm .3031   17.5mm .6890 m20x2.5
.25mm .0098   1.65mm .0650   11/64 .1719   7.75mm .3051 m9x1.25   45/64 .7031
87 .0100   1.7mm .0669   17 .1730   7.8mm .3171   18mm .7087 m20x2.0
.26mm .0102   51 .0670 #2-56   4.4mm .1732   7.9mm .3110   23/32 .7188 1/2-14  NPT PIPE
86 .0105   1.75mm .0689 m2.2x0.45   16 .1770 #12-24   5/16 .3125 3/8-16 NC   18.5mm .7283 m20x1.5
.27mm .0106   50 .0700 #2-64   4.5mm .1772   8mm .3150   47/64 .7344 1/2-14  NPS PIPE
85 .0110   1.8mm .0709   15 .1800   O .3160   19mm .7480
.28mm .0110   1.85mm .0728   4.6mm .1811   8.1mm .3189   3/4 .7500
.29mm .0114   49 .0730   14 .1820 #12-28   8.2mm .3228   49/64 .7656 7/8-9 NC
84 .0115   1.9mm .0748 m2.3x0.4   13 .1850   P .3230   19.5mm .7677 m22x2.5
.3mm .0118   48 .0760   4.7mm .1850   8.25mm .3248   25/32 .7812
83 .0120   1.95mm .0768   4.75mm .1870   8.3mm .3268   20mm .7874 m22x2.0
82 .0125   5/64 .0781   3/16 .1875   21/64 .3281   51/64 .7969
.32mm .0126   47 .0785 #3-48   4.8mm .1890   8.4mm .3307   20.5mm .8071 m22x1.5
81 .0130   2mm .0787   12 .1890 7/32-32 NS   Q .3320 3/8-24 NF   13/16 .8125 7/8-14 NF
.34mm .0134   2.05mm .0807 m2.5x45   11 .1910   8.5mm .3346 m10x1.5   21mm .8268 m24-3
80 .0135   46 .0810     4.9mm .1929   8.6mm .3386   53/64 .8281
.35mm .0138   45 .0820 #3-56   10 .1935   R .3390 1/8-27   NPT PIPE   27/32 .8438
.36mm .0142   2.1mm .0827   9 .1960   8.7mm .3425   21.5mm .8465
79 .0145   2.15mm .0846 m2.6x0.45   5mm .1969 m6x1   11/32 .3438   55/64 .8594
.38mm .0150   44 .0860 #4-36   8 .1990   8.75mm .3445 m10x1.25   22mm .8661 m24x2
1/64 .0156   2.2mm .0866   5.1mm .2008   8.8mm .3465   7/8 .8750 1-8 NC
.4mm .0157   2.25mm .0886   7 .2010 1/4-20   S .3480 1/8-27   NPS PIPE   22.25mm .8760
78 .0160   43 .0890 #4-40   13/64 .2031   8.9mm .3504   22.5mm .8858 m24x1.50
.42mm .0165   2.3mm .0906   6 .2040   9mm .3543 m10.x1.00   57/64 .8906
.44mm .0173   2.35mm .0925   5.2mm .2047   T .3580   23mm .9055
.45mm .0177   42 .0935 #4-48   5 .2055   9.1mm .3583   29/32 .9062
77 .0180   3/32 .0938   5.25mm .2067 m6x0.75   23/64 .3594   59/64 .9219 3/4-14  NPT PIPE
.46mm .0181   2.4mm .0945   5.3mm .2087   9.2mm .3622   23.5mm .9252
.48mm .0189   41 .0960   4 .2090 1/4-20   9.25mm .3642   15/16 .9375 3/4-14  NPS PIPE  1-1/4 NF
.5mm .0197   2.45mm .0965   5.4mm .2126   9.3mm .3661   24mm .9449
76 .0200   40 .0980   3 .2130 1/4-28   U .3680 7/16-14 NC   61/64 .9531
75 .0210   2.5mm .0984 m3-0.5   5.6mm .2165   9.4mm .3701   24.5mm .9646
.55mm .0217   39 .0995   7/32 .2188   9.5mm .3740 m11x1.5   31/32 .9688
74 .0225   38 .1015 #5-40   5.6mm .2205   3/8 .3750   25mm .9843 m27-2
.6mm .0236   2.6mm .1024   2 .2210   V .3770   63/64 .9844 1-1/8-7 NC
73 .0240   37 .1040 #5-44   5.7mm .2244   9.6mm .3780   1 1.0000
72 .0250   2.7mm .1063   5.75mm .2264   9.7mm .3819   25.5mm 1.0039
.65mm .0256   36 .1065 #6-32   1 .2280   9.75mm .3839   1-1/64 1.0156
71 .0260   2.75mm .1083   5.8mm .2283   9.8mm .3858   26mm 1.0236
.7mm .0276   7/64 .1094   5.9mm .2323   W .3860   1-1/32 1.0312
70 .0280   35 .1100   A .2340   9.9mm .3898   26.5mm 1.0433 m30x3.5
69 .0292   2.8mm .1102   15/64 .2344   25/64 .3906 7/16-20   1-3/64 1.0469 1-1/8-12 NF
.75mm .0295   34 .1110   6mm .2362 m7x1   10mm .3937 m12x1.75   1-1/16 1.0625
68 .0310   33 .1130 #6-40   B .2380   X .3970   27mm 1.0630
1/32 .0312   2.9mm .1142 m3.5x0.6   6.1mm .2402   Y .4040   1-5/64 1.0781
.8mm .0315   32 .1160   C .2420   13/32 .4062   27.5mm 1.0827
67 .0320   3mm .1181   6.2mm .2441   Z .4130   1-3/32 1.0928
66 .0330   31 .1200   D .2460 1/16-27 NPT PIPE   10.5mm .4134 m12x1.25   28mm 1.1024 m30x2.0
.85mm .0335   3.1mm .1220   6.25mm .2461   27/64 .4219 1/2-13   1-7/64 1.1094 1-1/4-7 NC
65 .0350   1/8 .1250 5/32-32 NS   6.3mm .2480   11mm .4331   28.5mm 1.1220
.9mm .0354   3.2mm .1260   E .2500   7/16 .4375 1/4-18   NPT PIPE   1-1/8 1.1250
64 .0360   3.25mm .1280   1/4 .2500 1/16-27 NPS PIPE   11.5mm .4528   1-9/64 1.1406
63 .0370   30 .1285 5/32-36 NS   6.4mm .2520   29/64 .4531 1/4-18   NPS PIPE  1/2-20   29mm 1.1417
.95mm .0374   3.3mm .1299 m4x0.7   6.5mm .2559   15/32 .4688   1-5/32 1.1562 1-11-1/2  NPT PIPE
62 .0380   3.4mm .1339   F .2570 5/16-18 NC   12mm .4724 m14x2   29.5mm 1.1614
61 .0390   29 .1360 #8-32   6.6mm .2598   31/64 .4844 9/16-12   1-11/64 1.1719 1-1/4-12 NF
1mm .0394   3.5mm .1378   G .2610   12.5mm .4921 m14x1.5  
60 .0400   28 .1405   6.7mm .2638   1/2 .5000  
59 .0410   9/64 .1406   17/64 .2638   13mm .5118 m14x1.25  
1.05mm .0413     3.6mm .1417     6.75mm .2656 m8x1.25   33/64 .5156 9/16-18