Imperial to Metric Conversion Chart for Common Luthiery Sizes

OK, I admit it, I just don’t get the imperial size thing although I accept I have to use it. This page is just for me and my inability to convert in my head 🙂

 

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

 

Inches Millimetres
1″ 25.4 mm
1/2″ 12.7 mm
1/4″ 6.35 mm
3/4″ 19.05 mm
5/8″ 15.875 mm
7/16″ 11.113 mm
5/32″ 3.97 mm
3/16″ 4.76 mm
7/32″ 5.55 mm
3/8″ 9.52 mm

 

Router Bit (1/4″ shank, D x L) Part Code / Supplier Notes
1/2″ x 1/2″ TB Pocket Routing and Profiling
1/2″ x 3/4″ TB 12799 TS Pocket Routing and Profiling
1/2″ x 1″ TB 85323 TS Deep Pocket Routing
1/2″ x 1″ BB 45755 TS Profiling
6mm  x 20mm 83429 TS Truss Rod Slot for Warman Truss Rod
1/4″ x 1″ 20708 TS Alternative for Warman Truss Rod, slightly bigger but should be fine
7/16″ x 1″  38758 TS  Truss Rod Slot for Allparts Truss Rod
1/4″ -> 1/2″ RO for Body Edge Radius

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