Fraction, Decimal & Millimeter Equivalents

  
mm to Inch
Conversion Chart
mm Inches (approximate)
  Simple
Conversion
To the nearest
1/32 inch
Decimal
1   1/32   1/32 0.04
2   1/16   3/32 0.08
3   1/8   4/32 0.12
4   3/16   5/32 0.16
5   3/16   6/32 0.20
6   1/4   8/32 0.24
7   1/4   9/32 0.28
8   5/16  10/32 0.31
9   3/8  11/32 0.35
10   3/8  13/32 0.39
11   7/16  14/32 0.43
12   1/2  15/32 0.47
13   1/2  16/32 0.51
14   9/16  18/32 0.55
15   9/16  19/32 0.59
16  5/8  20/32 0.63
17  11/16  21/32 0.67
18  11/16  23/32 0.71
19  3/4  24/32 0.75
20  13/16  25/32 0.79
21  13/16  26/32 0.83
22  7/8  28/32 0.87
23  7/8  29/32 0.91
24  15/16  30/32 0.94
25 1       31/32 0.98
26 1 1/32 1  1/32 1.02
27 1  1/16 1  2/32 1.06
28 1  1/8 1  3/32 1.10
29 1  1/8 1  5/32 1.14
30 1  3/16 1  6/32 1.18
31 1  1/4 1  7/32 1.22
32 1  1/4 1  8/32 1.26
33 1  5/16 1 10/32 1.30
34 1  5/16 1 11/32 1.34
35 1  6/16 1 12/32 1.38
36 1  7/16 1 13/32 1.42
37 1  7/16 1 15/32 1.46
38 1  8/16 1 16/32 1.50
39 1  9/16 1 17/32 1.54
40 1  9/16 1 18/32 1.57
41 1 10/16 1 20/32 1.61
42 1 10/16 1 21/32 1.65
43 1 11/16 1 22/32 1.69
44 1 12/16 1 23/32 1.73
45 1 12/16 1 25/32 1.77
46 1 13/16 1 26/32 1.81
47 1 14/16 1 27/32 1.85
48 1 14/16 1 28/32 1.89
49 1 15/16 1 30/32 1.93
50 1 15/16 1 31/32 1.97
51 2      2      2.01
Machine Screw
Size
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

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