Watch movement sizes
Home Up Removing the balance wheel Mainspring and barrel Checking watch bushings Cleaning watch dials Click and ratchet Popular watch crown styles Checking wheel and pinion depth English fusee cross section view Fitting odd shaped crystals Fitting round plastic watch crystals Fitting stems and crowns Pictures and drawingsl Watch jewels and pallets Keyless work winding and setting Letting down the mainspring pivotshake Pocket watch nomenclature Polishing plastic watch crystals Positional timing problems TECH HELP Refinishing hands Removing the dial Removing hands Removing motion work Removing movement Removing stem Repairing Enameled Dials some erratic operation causes Watch is gaining Straightening hands Transmision wheel Using calipers Watch movement sizes watch nomenclature watchcleaning Watch is slow Wheels and bridges Winding parts

 

CWR Technical Pages

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