Custom Thermoelectric - Peltier

Screws, Threads, Taps, & Drills

 


The Basics

Drill bits come in three US/English size groups and one Metric size group.

The three US/English size groups are;

  1. Fractional sizes (such as 1/16", 1/8", 1/4", etc.)
  2. Letter sizes (such as D, F, H, etc.)
  3. Wire Gage or Number sizes (such as 27, 44, 10, etc.)

The Metric size group simply uses the diameter of the drill bit as a designation. (such as 1.0mm, 3.2mm, 12.7mm, etc.)


How to use these Tables

Look down the left most column to find the screw size that you will be tapping a hole for or drilling a clearance hole for. Read across in the same row to find the drill size for the material you will be drilling in. If you need a clearance hole, then read across further to find the drill size for either a close fitting hole or a loose fitting hole.

Example:
You will be using a 6-32 machine screw. Looking at the first table "US English Table", look down the left most column under "Machine Screw Size" until you come to "6". Continue across in the same horizontal row. The next column shows ".1380" which is the maximum diameter of a # 6 screw. The 3rd column "Number of Threads per Inch" indicates a choice of either 32 or 40. Choose "32" since you have a 6-32 screw. Stay in this sub-row and continue on rightward. The "Minor Diameter" is the diameter of a 6-32 from screw thread trough to screw thread trough. Now, to tap a thread, choose either "Aluminum, Brass & Plastics" for softer materials or "Stainless Steel, Steels & Iron" for harder materials depending on the material you have. If you do not need to Tap, but just drill a Clearance hole, then choose between "Close Fit" or "Free Fit". For tapping Aluminum, the drill size indicates a "36" drill. For a clearance close fit hole, the drill size indicates a "27".

 

Jump to the following tables

US English Table

Metric Table

Pipe Thread Table

Decimal Equivalents of all Drill Sizes Table

 

On small screens, scroll sideways for the following tables.

US / English Tap Drill Table

Machine Screw Size
Number of Threads Per Inch
Minor Dia.
Tap Drills
Clearance Hole Drills

Aluminum, Brass & Plastics

75% Thread

Stainless Steel, Steels & Iron

50% Thread

All Materials
Close Fit
Free Fit
No. or Dia.
Major Dia.
Drill Size
Decimal Equiv.
Drill Size
Decimal Equiv.
Drill Size
Decimal Equiv.
Drill Size
Decimal Equiv.
0
.0600
80
.0447
3/64
.0469
55
.0520
52
.0635
50
.0700
1
.0730
64
.0538
53
.0595
1/16
.0625
48
.0760
46
.0810
72 .0560 53 .0595 52 .0635
2 .0860 56 .0641 50 .0700 49 .0730 43 .0890 41 .0960
64 .0668 50 .0700 48 .0760
3 .0990 48 .0734 47 .0785 44 .0860 37 .1040 35 .1100
56 .0771 45 .0820 43 .0890
4 .1120 40 .0813 43 .0890 41 .0960 32 .1160 30 .1285
48 .0864 42 .0935 40 .0980
5 .1250 40 .0943 38 .1015 7/64 .1094 30 .1285 29 .1360
44 .0971 37 .1040 35 .1100
6 .1380 32 .0997 36 .1065 32 .1160 27 .1440 25 .1495
40 .1073 33 .1130 31 .1200
8 .1640 32 .1257 29 .1360 27 .1440 18 .1695 16 .1770
36 .1299 29 .1360 26 .1470
10 .1900 24 .1389 25 .1495 20 .1610 9 .1960 7 .2010
32 .1517 21 .1590 18 .1695
12 .2160 24 .1649 16 .1770 12 .1890 2 .2210 1 .2280
28 .1722 14 .1820 10 .1935
32 .1777 13 .1850 9 .1960
1/4 .2500 20 .1887 7 .2010 7/32 .2188 F .2570 H .2660
28 .2062 3 .2130 1 .2280
32 .2117 7/32 .2188 1 .2280
5/16 .3125 18 .2443 F .2570 J .2770 P .3230 Q .3320
24 .2614 I .2720 9/32 .2812
32 .2742 9/32 .2812 L .2900
3/8 .3750 16 .2983 5/16 .3125 Q .3320 W .3860 X .3970
24 .3239 Q .3320 S .3480
32 .3367 11/32 .3438 T .3580
7/16 .4375 14 .3499 U .3680 25/64 .3906 29/64 .4531 15/32 .4687
20 .3762 25/64 .3906 13/32 .4062
28 .3937 Y .4040 Z .4130
1/2 .5000 13 .4056 27/64 .4219 29/64 .4531 33/64 .5156 17/32 .5312
20 .4387 29/64 .4531 15/32 .4688
28 .4562 15/32 .4688 15/32 .4688
9/16 .5625 12 .4603 31/64 .4844 33/64 .5156 37/64 .5781 19/32 .5938
18 .4943 33/64 .5156 17/32 .5312
24 .5114 33/64 .5156 17/32 .5312
5/8 .6250 11 .5135 17/32 .5312 9/16 .5625 41/64 .6406 21/32 .6562
18 .5568 37/64 .5781 19/32 .5938
24 .5739 37/64 .5781 19/32 .5938
11/16 .6875 24 .6364 41/64 .6406 21/32 .6562 45/64 .7031 23/32 .6562
3/4 .7500 10 .6273 21/32 .6562 11/16 .6875 49/64 .7656 25/32 .7812
16 .6733 11/16 .6875 45/64 .7031
20 .6887 45/64 .7031 23/32 .7188
13/16 .8125 20 .7512 49/64 .7656 25/32 .7812 53/64 .8281 27/32 .8438
7/8 .8750 9 .7387 49/64 .7656 51/64 .7969 57/64 .8906 29/32 .9062
14 .7874 13/16 .8125 53/64 .8281
20 .8137 53/64 .8281 27/32 .8438
15/16 .9375 20 .8762 57/64 .8906 29/32 .9062 61/64 .9531 31/32 .9688
1 1.000 8 .8466 7/8 .8750 59/64 .9219 1-1/64 1.0156 1-1/32 1.0313
12 .8978 15/16 .9375 61/64 .9531
20 .9387 61/64 .9531 31/32 .9688
1-1/16 1.0625 18 .9943 1.000 1.000 1-1/64 1.0156 1-5/64 1.0781 1-3/32 1.0938
1-1/8 1.1250 7 .9497 63/64 .9844 1-1/32 1.0313 1-9/64 1.1406 1-5/32 1.1562
12 1.0228 1-3/64 1.0469 1-5/64 1.0781
18 1.0568 1-1/16 1.0625 1-5/64 1.0781
1-3/16 1.1875 18 1.1193 1-1/8 1.1250 1-9/64 1.1406 1-13/64 1.2031 1-7/32 1.2188
1-1/4 1.2500 7 1.0747 1-7/64 1.1094 1-5/32 1.1562 1-17/64 1.2656 1-9/32 1.2812
12 1.1478 1-11/64 1.1719 1-13/64 1.2031
18 1.1818 1-3/16 1.1875 1-13/64 1.2031
1-5/16 1.3125 18 1.2443 1-1/4 1.2500 1-17/64 1.2656 1-21/64 1.3281 1-11/32 1.3438
1-3/8 1.3750 6 1.1705 1-7/32 1.2187 1-17/64 1.2656 1-25/64 1.3906 1-13/32 1.4062
12 1.2728 1-19/64 1.2969 1-21/64 1.3281
18 1.3068 1-5/16 1.3125 1-21/64 1.3281
1-7/16 1.4375 18 1.3693 1-3/8 1.3750 1-25/64 1.3906 1-29/64 1.4531 1-15/32 1.4688
1-1/2 1.500 6 1.2955 1-11/32 1.3437 1-25/64 1.3906 1-33/64 1.5156 1-17/32 1.5312
12 1.3978 1-27/64 1.4219 1-7/16 1.4375
18 1.4318 1-7/16 1.4375 1-29/64 1.4531
1-9/16 1.5625 18 1.4943 1-12 1.500 1-33/64 1.5156 1-37/64 1.5781 1-19/32 1.5938
1-5/8 1.625 18 1.5568 1-9/16 1.5625 1-37/64 1.5781 1-41/64 1.6406 1-21/32 1.6562
1-11/16 1.6875 18 1.6193 1-5/8 1.6250 1-41/64 1.6406 1-45/64 1.7031 1-23/32 1.7188
1-3/4 1.750 5 1.5046 1-9/16 1.5625 1-5/8 1.6250 1-49/64 1.7659 1-25/32 1.7812

 

 

On small screens, scroll sideways for the following tables.

Metric Tap Drill Table

Tap size Major
Dia (mm)
Threads
per mm
Tap Drill
(mm)
Tap Drill
(inch)
Clearance
(mm)
Clearance
(inch)
M1.6x0.35 1.6 0.35 1.25 55 1.8 49
M2x0.4 2.0 0.40 1.60 52 2.4 41
M2.5x0.45 2.5 0.45 2.05 46 2.9 32
M3x.05 3.0 0.50 2.50 39 3.4 29
M3.5x0.6 3.5 0.60 2.90 32 3.9 23
M4x0.7 4.0 0.70 3.30 30 4.5 16
M5x0.8 5.0 0.80 4.20 19 5.5 7/32
M6x1 6.0 1.00 5.0 8 6.6 G
M8x1.25 8.0 1.25 6.8 H 9.0 T
M8x1 8.0 1.00 7.0 J 9.0 T
M10x1.5 10.0 1.50 8.5 R 12.0 31/64
M10x1.25 10.0 1.25 8.8 11/32 12.0 31/64
M12x1.75 12.0 1.75 10.2 13/32 14.0 35/64
M12x1.25 12.0 1.25 10.8 27/64 14.0 35/64
M14x2 14.0 2.00 12.0 15/32 16.0 5/8
M14x1.5 14.0 1.5 12.5 1/2 16.0 5/8
M16x2 16.0 2.00 14.0 35/64 18.0 45/64
M16x1.5 16.0 1.50 14.5 37/64 18.0 45/64
M18x2.5 18.0 2.50 15.5 39/64 20.0 51/64
M18x1.5 18.0 1.50 16.5 21/32 20.0 51/64
M20x2.5 20.0 2.50 17.5 11/16 22.0 7/8
M20x1.5 20.0 1.50 18.5 47/64 22.0 7/8
M22x2.5 22.0 2.50 19.5 49/64 25.0 1
M22x1.5 22.0 1.50 20.5 13/16 25.0 1
M24x3 24.0 3.00 21.0 53/64 27.0 1-5/64
M24x2 24.0 2.00 22.0 7/8 27.0 1-5/64
M27x3 27.0 3.00 24.0 15/16 30.0 1-3/16
M27x2 27.0 2.0 25.0 1 30.0 1-3/16

 

 

On small screens, scroll sideways for the following tables.

Pipe Thread Tap Drill Table

- American Standard British Standard
Nominal
OD
Threads
per inch
NPT NPS Threads
per inch
Drill size
1/16 27 D 1/4 28 G
1/8 27 R S 28 11/32
1/4 18 7/16 29/64 19 15/32
3/8 18 37/64 19/32 19 39/64
1/2 14 23/32 47/64 14 3/4
5/8 - - - 14 53/64
3/4 14 59/64 15/16 14 31/32
7/8 - - - 14 1-7/64
1 11.5 1-5/32 1-3/16 11 1-7/32

 

 

On small screens, scroll sideways for the following tables.

Decimal Equivalents of Drill Sizes up to 1-1/4" (31.75mm)

Fractional
Drill Sizes
(inches)
Decimal
Equivalent
(inches)
Wire and
Letter Drill
Sizes
mm
Drill
Sizes
  .0059 97 .15
  .0063 96 .16
  .0067 95 .17
  .0071 94 .18
  .0075 93 .19
  .0079 92 .20
  .0083 91 .21
  .0087 90 .22
  .0091 89 .23
  .0094   .24
  .0095 88  
  .0098   .25
  .0100 87  
  .0102   .26
  .0105 86  
  .0106   .27
  .0110 85 .28
  .0114   .29
  .0115 84  
  .0118   .30
  .0120 83  
  .0125 82  
  .0126   .32
  .0130 81  
  .0134   .34
  .0135 80  
  .0138   .35
  .0142   .36
  .0145 79  
  .0150   .38
1/64 .0156    
  .0157   .40
  .0160 78  
  .0165   .42
  .0173   .44
  .0177   .45
  .0180 77  
  .0181   .46
  .0189   .48
  .0197   .50
  .0200 76  
  .0210 75  
  .0217   .55
  .0225 74  
  .0236   .60
  .0240 73  
  .0250 72  
  .0256   .65
  .0260 71  
  .0276   .70
  .0280 70  
  .0292 69  
  .0295   .75
  .0310 68  
1/32 .0312    
  .0315   .80
  .0320 67  
  .0330 66  
  .0335   .85
  .0350 65  
  .0354   .90
  .0360 64  
  .0370 63  
  .0374   .95
  .0380 62  
  .0390 61  
  .0394   1.00
  .0400 60  
  .0410 59  
  .0413   1.05
  .0420 58  
  .0430 57  
  .0433   1.10
  .0453   1.15
  .0465 56  
3/64 .0469    
  .0472   1.20
  .0492   1.25
  .0512   1.30
  .0520 55  
  .0531   1.35
  .0550 54  
  .0551   1.40
  .0571   1.45
  .0591   1.50
  .0595 53  
  .0610   1.55
1/16 .0625    
  .0630   1.60
  .0635 52  
  .0650   1.65
  .0669   1.70
  .0670 51  
  .0689   1.75
  .0700 48  
  .0709   1.80
  .0728   1.85
  .0730 49  
  .0748   1.90
  .0760 48  
  .0768   1.95
5/64 .0781    
  .0785 47  
  .0787   2.00
  .0807   2.05
  .0810 46  
  .0820 45  
  .0827   2.10
  .0846   2.15
  .0860 44  
  .0866   2.20
  .0886   2.25
  .0890 43  
  .0906   2.30
  .0925   2.35
  .0935 42  
3/32 .0938    
  .0945   2.40
  .0960 41  
  .0965   2.45
  .0980 40  
  .0984   2.50
  .0995 39  
  .1015 38  
  .1024   2.60
  .1040 37  
  .1063   2.70
  .1065 36  
  .1083   2.75
7/64 .1094    
  .1100 35  
  .1102   2.80
  .1110 34  
  .1130 33  
  .1142   2.90
  .1160 32  
  .1181   3.00
  .1200 31  
  .1220   3.10
1/8 .1250    
  .1260   3.20
  .1280   3.25
  .1285 30  
  .1299   3.30
  .1339   3.40
  .1360 29  
  .1378   3.50
  .1405 28  
9/64 .1406    
  .1417   3.60
  .1440 27  
  .1457   3.70
  .1470 26  
  .1476   3.75
  .1495 25  
  .1496   3.80
  .1520 24  
  .1535   3.90
  .1540 23  
5/32 .1562    
  .1570 22  
  .1575   4.00
  .1590 21  
  .1610 20  
  .1614   4.10
  .1654   4.20
  .1660 19  
  .1673   4.25
  .1693   4.30
  .1695 18  
11/64 .1719    
  .1730 17  
  .1732   4.40
  .1770 16  
  .1772   4.50
  .1800 15  
  .1811   4.60
  .1820 14  
  .1850 13 4.70
  .1870   4.75
3/16 .1875    
  .1890 12 4.80
  .1910 11  
  .1929   4.90
  .1935 10  
  .1960 9  
  .1969   5.00
  .1990 8  
  .2008   5.10
  .2010 7  
13/64 .2031    
  .2040 6  
  .2047   5.20
  .2055 5  
  .2067   5.25
  .2087   5.30
  .2090 4  
  .2126   5.40
  .2130 3  
  .2165   5.50
7/32 .2188    
  .2205   5.60
  .2210 2  
  .2244   5.70
  .2264   5.75
  .2280 1  
  .2283   5.80
  .2323   5.90
  .2340 A  
15/64 .2344    
  .2362   6.00
  .2380 B  
  .2402   6.10
  .2420 C  
  .2441   6.20
  .2460 D  
  .2461   6.25
  .2480   6.30
1/4 .2500 E 6.35
  .2520   6.40
  .2559   6.50
  .2570 F  
  .2598   6.60
  .2610 G  
  .2638   6.70
17/64 .2656    
  .2657   6.75
  .2660 H  
  .2677   6.80
  .2717   6.90
  .2720 I  
  .2756   7.00
  .2770 J  
  .2795   7.10
  .2810 K  
9/32 .2812    
  .2835   7.20
  .2854   7.25
  .2874   7.30
  .2900 L  
  .2913   7.40
  .2950 M  
  .2953   7.50
19/64 .2969    
  .2992   7.60
  .3020 N  
  .3031   7.70
  .3051   7.75
  .3071   7.80
  .3110   7.90
5/16 .3125    
  .3150   8.00
  .3160 O  
  .3189   8.10
  .3228   8.20
  .3230 P  
  .3248   8.25
  .3268   8.30
21/64 .3281    
  .3307   8.40
  .3320 Q  
  .3346   8.50
  .3386   8.60
  .3390 R  
  .3425   8.70
11/32 .3438    
  .3445   8.75
  .3465   8.80
  .3480 S  
  .3504   8.90
  .3543   9.0
  .3580 T  
  .3583   9.10
23/64 .3594    
  .3622   9.20
  .3642   9.25
  .3661   9.30
  .3680 U  
  .3701   9.40
  .3740   9.50
3/8 .3750    
  .3770 V  
  .3780   9.60
  .3819   9.70
  .3839   9.75
  .3858   9.80
  .3860 W  
  .3898   9.90
25/64 .3906    
  .3937   10.0
  .3970 X  
  .4040 Y  
13/32 .4062    
  .4130 Z  
  .4134   10.5
27/64 .4219    
  .4330   11.0
7/16 .4375    
  .4528   11.5
29/64 .4531    
15/32 .4668    
  .4724   12.0
31/64 .4844    
  .4921   12.5
1/2 .5000   12.7
  .5118   13.0
33/64 .5156    
17/32 .5312    
  .5315   13.5
35/64 .5469    
  .5512   14.0
9/16 .5625    
  .5709   14.5
37/64 .5781    
  .5906   15.0
19/32 .5938    
39/64 .6094    
  .6102   15.5
5/8 .6250    
  .6299   16.0
41/64 .6406    
  .6496   16.5
21/32 .6562    
  .6693   17.0
43/64 .6719    
11/16 .6875    
  .6890   17.5
45/64 .7031    
  .7087   18.0
23/32 .7188    
  .7283   18.5
47/64 .7344    
  .7480   19.0
3/4 .7500   19.05
49/64 .7656    
  .7677   19.5
25/32 .7812    
  .7874   20.0
51/64 .7969    
  .8071   20.5
13/16 .8125    
  .8268   21.0
53/64 .8281    
27/32 .8438    
  .8465   21.5
55/64 .8594    
  .8661   22.0
7/8 .8750    
  .8858   22.5
57/64 .8906    
  .9055   23.0
29/32 .9062    
59/64 .9219    
  .9252   23.5
15/16 .9375    
  .9449   24.0
61/64 .9531    
  .9646   24.5
31/32 .9688    
  .9843   25.0
63/64 .9844    
1 1.0000   25.4
  1.0039   25.5
1-1/64 1.0156    
  1.0236   26.0
1-1/32 1.0312    
  1.0433   26.5
1-3/64 1.0469    
1-1/16 1.0625    
  1.0630   27.0
1-5/64 1.0781    
  1.0827   27.5
1-3/32 1.0938    
  1.1024   28.0
1-7/64 1.1094    
  1.1220   28.5
1-1/8 1.1250    
1-9/64 1.1406    
  1.1417   29.0
1-5/32 1.1562    
  1.1614   29.5
1-11/64 1.1719    
  1.1811   30.0
1-3/16 1.1875    
  1.1910   30.25
  1.2008   30.5
1-13/64 1.2031    
  1.2107   30.75
1-7/32 1.2188    
  1.2205   31.0
  1.2304   31.25
1-15/64 1.2344    
  1.2402   31.5
1-1/4 1.2500   31.75