Watch movement size conversion chart

Watch movement size conversion chart

 

There are three major ways in which watch movements are measured Ligne, mm, and American.

 

1 ligne = 2.256 mm.

 

American movement sizes to Ligne to mm conversion

Size             Ligne                mm

18/0            6 3/4            15.25

17/0            1 1/8            16.08

16/0            7 1/2            16.92

15/0            7 7/8            17.78

14/0            8 1/4            18.62

13/0            8 5/8            19.46

12/0            9 1/8            20.32

11/0            9 3/8            21.16

10/0            9 3/4            22.00

  9/0          10 1/8            22.86

   8/0          10 1/2            23.70

   7/0          10 7/8            24.54

   6/0          11 1/4            25.40

   5/0          11 5/8            26.24

   4/0          12 1/8            27.08

   3/0          12 3/8            27.94

   2/0          12 3/4            28.78

   0              13 1/8            29.62

   1              13 1/2            30.48

   2              13 7/8            31.32

   3              14 1/4            32.16

   4              14 7/8            33.02

   5              15 1/8            33.86

   6              15 3/8            34.70

   7              15 3/4            35.56

   8              16 1/8            36.40

   9              16 1/2            37.24

10              16 7/8            38.10

11              17 1/4            38.94

12              17 5/8            39.78

13              18 1/8            40.64

14              18 3/8            41.48

15              18 3/4            42.32

16              19 1/8            43.18

17              19 1/2            44.02

18              19 7/8            44.86

19              20 1/4            45.72

20              20 3/4            46.56 

 

Swiss movement sizes, Ligne to mm conversion

Lignes              mm

  7                           15.79

  8                           18.05

  9                           20.30

10                           22.56

11                           24.81

12                           27.07

13                           29.32

14                           31.58

15                           33.84

16                           36.09

17                           38.35

18                           40.60

19                           42.86

20                           45.11

21                           47.37

22                           49.63

 

Common American movement sizes

26/0, 22/0, 21/0, 20/0, 18/0, 16/0, 15/0, 14/0, 12/0, 10/0, 8/0, 6/0, 5/0, 4/0, 3/0,  0,  6,, 8, 10, 12, 14, 16, 18

 

Common Swiss movement sizes ( * sizes are most common )

Lignes                mm

 3 3/4 x 6 3/4            9.0 x 15.15

 3 3/4 x 8 1/4            9.0 x 19.4

 3 3/4 x 10                 9.0 x 21.0

*5 1/2 x 6 3/4            13.0 x 15.15

*6 3/4 x 8                   15.3 x 17.8

*7 3/4                         17.2

8 1/4                         18.2

*8 3/4                         19.4

*10 1/2                       23.3

*11 1/2                       25.6

12 1/2                       28.4

16 1/2                       36.6