Reference Library

Pocket Watch Size Chart
Use the size chart below to determine the size of your watch by carefully measuring the pillar plate (dial side) diameter of the movement with a micrometer.
The sizing system utilized by American watch companies is derived from the Lancashire Gauge, popularized in the English watchmaking trade. One inch is taken as a basing figure and 5/30 of an inch is added for the fall or drop of the dial, resulting in 1 5/30 of an inch referred to as "naught size” (0s). Subsequently, the addition or subtraction of each 1/30” increment results in scaling the size up or down. For example, size 12 measures 1 17/30” (12 increments of 1/30” from the naught size of 1 5/30”).
Note: Companies did not strictly adhere to this sizing standard, using a 6/30" drop instead of the 5/30" for larger movements. As a result, “18 Size” American movements are actually 19 Size according to the Lancashire Gauge system.
Size | Diameter (Millimeters) | Diameter (Inches) | Diameter (Inches, Fraction) | |
---|---|---|---|---|
21/0s | 12.70 mm | 0.500 in | 1/2 in | |
20/0s | 13.55 mm | 0.533 in | 8/15 in | |
19/0s | 14.39 mm | 0.567 in | 17/30 in | |
18/0s | 15.24 mm | 0.600 in | 3/5 in | |
17/0s | 16.09 mm | 0.633 in | 19/30 in | |
16/0s | 16.93 mm | 0.667 in | 2/3 in | |
15/0s | 17.78 mm | 0.700 in | 7/10 in | |
14/0s | 18.63 mm | 0.733 in | 11/15 in | |
13/0s | 19.47 mm | 0.767 in | 23/30 in | |
12/0s | 20.32 mm | 0.800 in | 4/5 in | |
11/0s | 21.17 mm | 0.833 in | 5/6 in | |
10/0s | 22.01 mm | 0.867 in | 13/15 in | |
9/0s | 22.86 mm | 0.900 in | 9/10 in | |
8/0s | 23.71 mm | 0.933 in | 14/15 in | |
7/0s | 24.55 mm | 0.967 in | 29/30 in | |
6/0s | 25.40 mm | 1.000 in | 1 in | |
5/0s | 26.25 mm | 1.033 in | 1 1/30 in | |
4/0s | 27.09 mm | 1.067 in | 1 1/15 in | |
3/0s | 27.94 mm | 1.100 in | 1 1/10 in | |
2/0s | 28.79 mm | 1.133 in | 1 2/15 in | |
0s | 29.63 mm | 1.167 in | 1 1/6 in | |
1s | 30.48 mm | 1.200 in | 1 1/5 in | |
2s | 31.33 mm | 1.233 in | 1 7/30 in | |
3s | 32.17 mm | 1.267 in | 1 4/15 in | |
4s | 33.02 mm | 1.300 in | 1 3/10 in | |
5s | 33.87 mm | 1.333 in | 1 1/3 in | |
6s | 34.71 mm | 1.367 in | 1 11/30 in | |
7s | 35.56 mm | 1.400 in | 1 2/5 in | |
8s | 36.41 mm | 1.433 in | 1 13/30 in | |
9s | 37.25 mm | 1.467 in | 1 7/15 in | |
10s | 38.10 mm | 1.500 in | 1 1/2 in | |
11s | 38.95 mm | 1.533 in | 1 8/15 in | |
12s | 39.79 mm | 1.567 in | 1 17/30 in | |
13s | 40.64 mm | 1.600 in | 1 3/5 in | |
14s | 41.49 mm | 1.633 in | 1 19/30 in | |
15s | 42.33 mm | 1.667 in | 1 2/3 in | |
16s | 43.18 mm | 1.700 in | 1 7/10 in | |
17s | 44.03 mm | 1.733 in | 1 11/15 in | |
18s | 44.87 mm | 1.767 in | 1 23/30 in | |
Note: American 18s Movements Measure 1.800" Due to the Increased 6/30" Drop. | ||||
19s | 45.72 mm | 1.800 in | 1 4/5 in | |
20s | 46.57 mm | 1.833 in | 1 5/6 in | |
21s | 47.41 mm | 1.867 in | 1 13/15 in | |
22s | 48.26 mm | 1.900 in | 1 9/10 in | |
23s | 49.11 mm | 1.933 in | 1 14/15 in | |
24s | 49.95 mm | 1.967 in | 1 29/30 in | |
25s | 50.80 mm | 2.000 in | 2 in | |
26s | 51.65 mm | 2.033 in | 2 1/30 in | |
27s | 52.49 mm | 2.067 in | 2 1/15 in | |
28s | 53.34 mm | 2.100 in | 2 1/10 in | |
29s | 54.19 mm | 2.133 in | 2 2/15 in | |
30s | 55.03 mm | 2.167 in | 2 1/6 in | |
31s | 55.88 mm | 2.200 in | 2 1/5 in | |
32s | 56.73 mm | 2.233 in | 2 7/30 in | |
33s | 57.57 mm | 2.267 in | 2 4/15 in | |
34s | 58.42 mm | 2.300 in | 2 3/10 in | |
35s | 59.27 mm | 2.333 in | 2 1/3 in | |
36s | 60.11 mm | 2.367 in | 2 11/30 in |