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Metric to Imperial Chart

A reference chart comprising the standard and not so standard metric and imperial fastener sizes. With over 250 metric sizes, the chart displays the equivalent fraction and decimal number for easy cross referencing. Useful when you are trying to narrow the size down to the absolute closest mm or fraction of an inch.

Not to scale

Metric	Imperial
Millimetres (mm)	Fractional (in")	Decimal
0.1	-	0.0039
0.2	-	0.0079
0.3	-	0.0118
0.40	1/64	0.0156
0.4	-	0.0157
0.5	-	0.0197
0.6	-	0.0236
0.7	-	0.0276
0.79	1/32	0.0313
0.8	-	0.0315
0.9	-	0.0354
1	-	0.0394
1.1	-	0.0433
1.9	3/64	0.0469
1.2	-	0.0472
1.3	-	0.0512
1.4	-	0.0551
1.5	-	0.0591
1.59	1/16	0.0625
1.6	-	0.063
1.7	-	0.0669
1.8	-	0.0709
1.9	-	0.0748
1.98	5/64	0.0781
2	-	0.0787
2.1	-	0.0827
2.2	-	0.0866
2.3	-	0.0906
2.38	3/32	0.0938
2.4	-	0.0945
2.5	-	0.0984
2.78	7/64	0.1094
3	-	0.1181
3.18	1/8	0.125
3.5	-	0.1378
3.57	9/64	0.1406
3.97	5/32	0.1563
4	-	0.1575
4.37	11/64	0.1719
4.5	-	0.1772
4.76	3/16	0.1875
5	-	0.1969
5.16	13/64	0.2031
5.5	-	0.2165
5.56	7/32	0.2188
5.95	15/64	0.2344
6	-	0.2362
6.35	1/4	0.25
6.5	-	0.2559
6.75	17/64	0.2656
7	-	0.2756
7.14	9/32	0.2813
7.5	-	0.2953
7.54	19/64	0.2969
7.94	5/16	0.3125
8	-	0.315
8.33	21/64	0.3281
8.5	-	0.3346
8.73	11/32	0.3438
9	-	0.3543
9.13	23/64	0.3594
9.5	-	0.374
9.53	3/8	0.375
9.92	25/64	0.3906
10	-	0.3937
10.32	13/32	0.4063
10.5	-	0.4134
10.72	27/64	0.4219
11	-	0.4331
11.11	7/16	0.4375
11.5	-	0.4528
11.51	29/64	0.4531
11.91	15/32	0.4688
12	-	0.4724
12.30	31/64	0.4844
12.5	-	0.4921
12.7	1/2	0.5
13	-	0.5118
13.10	33/64	0.5156
13.49	17/32	0.5313
13.495	-	0.5315
13.89	35/64	0.5469

Metric	Imperial
Millimetres (mm)	Fractional (in")	Decimal
14	-	0.551
14.29	9/16	0.563
14.5	-	0.571
14.68	37/64	0.578
15	-	0.591
15.08	19/32	0.594
15.48	39/64	0.609
15.5	-	0.610
15.88	5/8	0.625
16	-	0.630
16.27	41/64	0.641
16.5	-	0.650
16.67	21/32	0.656
17	-	0.669
17.07	43/64	0.672
17.46	11/16	0.688
17.5	-	0.689
17.86	45/64	0.703
18	-	0.709
18.26	23/32	0.719
18.5	-	0.728
18.65	47/64	0.734
19	-	0.748
19.05	3/4	0.75
19.45	49/64	0.766
19.5	-	0.768
19.84	25/32	0.781
20	-	0.787
20.24	51/64	0.797
20.5	-	0.807
20.64	13/16	0.813
21	-	0.827
21.03	53/64	0.828
21.43	27/32	0.844
21.5	-	0.847
21.83	55/64	0.859
22	-	0.866
22.23	7/8	0.875
22.5	-	0.886
22.62	57/64	0.891
23	-	0.906
23.02	29/32	0.906
23.42	59/64	0.922
23.5	-	0.925
23.81	15/16	0.938
24	-	0.945
24.21	61/64	0.953
24.5	-	0.965
24.61	31/32	0.969
25.00	63/64	0.984
25.4	1	1
25.5	-	1.004
26	-	1.024
26.5	-	1.043
27	-	1.063
27.5	-	1.083
28	-	1.102
28.5	-	1.122
29	-	1.142
29.5	-	1.161
30	-	1.181
31	-	1.221
31,75	1-1/4	1.25
32	-	1.260
33	-	1.299
34	-	1.339
34.9	1-3/8	1.375
36	-	1.417
37	-	1.457
38	-	1.496
38.1	1-1/2	1.5
39	-	1.535
40	-	1.575
41	-	1.614
42	-	1.654
43	-	1.693
44	-	1.732
44.45	1-3/4	1.75
45	-	1.772
46	-	1.811
47	-	1.850
48	-	1.8898

Metric	Imperial
Millimetres (mm)	Fractional (in")	Decimal
49	-	1.9291
50	-	1.9685
50.8	2	2
51	-	2.0079
52	-	2.0472
53	-	2.0866
54	2-1/8	2.125
55	-	2.1654
56	-	2.2047
57	-	2.2441
57.15	2-1/4	2.25
58	-	2.2835
59	-	2.3228
60.3	2-3/8	2.3675
61	-	2.4016
62	-	2.4409
63	-	2.4803
63.5	2-1/2	2.5
64	-	2.5197
65	-	2.5591
66	-	2.5984
66.7	2-5/8	2.625
68	-	2.6772
69	-	2.7165
69.85	2-3/4	2.75
70	-	2.7559
71	-	2.7953
72	-	2.8346
73	-	2.874
74	-	2.9134
75	-	2.9528
76	-	2.9921
76.2	3	3
77	-	3.0315
78	-	3.0709
79	-	3.1102
80	-	3.1496
81	-	3.189
82	-	3.2283
83	-	3.2677
84	-	3.3071
85	-	3.3465
86	-	3.3858
87	-	3.4252
88	-	3.4646
88.9	3-1/2	3.5
89	-	3.5039
90	-	3.5433
91	-	3.5827
92	-	3.622
93	-	3.6614
94	-	3.7008
95	-	3.7402
96	-	3.7795
97	-	3.8189
98	-	3.8583
99	-	3.8976
100	-	3.937
101.6	4	4
110	-	4.3307
114.3	4-1/2	4.5
12	-	4.7244
127	5	5
130	-	5.1181
140	-	5.5118
150	-	5.9055
152.4	6	6
160	-	6.2992
170	-	6.6929
177.8	7	7
190	-	7.4803
200	-	7.87
203.2	8	8
250	-	9.84
254	10	10
279.4	11	11
304.8	12	12
330.02	13	13
355.6	14	14
381	15	15
508	20	20
635	25	25

Bold = Common fastener sizes

Download chart: Metric to Imperial Chart