Loading... Please wait...

Pocket Watch Sizes - How to measure a movement

Pocket Watch Sizes

Today’s modern pocket watches are measured in millimeters by measurement of the outside diameter of the case. This is because watches today are manufactured and sold with the case and watch movement together.

However this was not always the case as vintage American watches are measured differently. They are measured by the size of the watch movement inside the case. Back in the early days, pocket watch movements were sold to jewelers separately from the watch case. A customer would go to a jeweler and select the watch movement they liked and then would select a case to hold the movement. The jeweler would then assemble the watch for the customer. It was not uncommon for the case to be made by one manufacturer and the movement made by another. E.g. a size 16 watch movement would fit into a size 16 case.

Vintage watch movement sizes are determined by measuring the distance across the dial plate of the movement. This is not the measurement of the dial itself, but the measurement of the watch movement on the side where the dial is mounted. If the watch movement is oval or rectangle in shape, you would measure the narrowest part of the movement.

Pocket watch movements are sized using a system developed by English watchmakers called the Lancashire system or as its better know term, the Lancashire gauge. In this system a movement measuring 1 5/30 of an inch is called size 0 and each 1/30th of an inch added or subtracted changes the size by 1. Please see the convenient chart below to determine the size of your watch.

Watch Size

Inches Fractional

Inches Decimal

Lignes

Millimeters

18

1 23/30

1.766

19.87

44.86

17

1 22/30

1.733

19.50

44.02

16

1 21/30

1.700

19.12

43.17

15

1 20/30

1.666

18.75

42.33

14

1 19/30

1.633

18.37

41.48

13

1 18/30

1.600

18.00

40.63

12

1 17.30

1.566

17.62

39.79

11

1 16/30

1.533

17.25

38.94

10

1 15/30

1.500

16.87

38.09

9

1 14/30

1.466

16.50

37.25

8

1 13/30

1.433

16.12

36.40

7

1 12/30

1.400

15.75

35.55

6

1 11/30

1.366

15.37

34.71

5

1 10/30

1.333

15.00

33.86

4

1 9/30

1.300

14.62

33.01

3

1 8/30

1.266

14.25

32.17

2

1 7/30

1.233

13.87

31.32

1

1 6/30

1.200

13.50

30.47

0

1 5/30

1.166

13.12

29.63

2/0

1 4/30

1.133

12.75

28.78

3/0

1 3/30

1.100

12.37

27.93

4/0

1 2/30

1.066

12.00

27.09

5/0

1 1/30

1.033

11.62

26.24

6/0

1

1.000

11.25

25.39

7/0

29/30

0.966

10.87

24.55

8/0

28/30

0.933

10.50

23.70

9/0

27/30

0.900

10.12

22.85

10/0

26/30

0.866

9.75

22.01

11/0

25/30

0.833

9.37

21.16

12/0

24/30

0.800

9.00

20.31

13/0

23/30

0.766

8.62

19.47

14/0

22/30

0.733

8.25

18.62

15/0

21/30

0.700

7.87

17.77

16/0

20/30

0.666

7.50

16.93

17/0

19/30

0.633

7.12

16.08

18/0

18/30

0.600

6.75

15.23

19/0

17/30

0.566

6.37

14.39

20/0

16/30

0.533

6.00

13.54

21/0

15/30

0.500

5.62

12.69

22/0

14/30

0.466

5.25

11.85

23/0

13/30

0.433

4.87

11.00

24/0

12/30

0.400

4.50

10.15

25/0

11/30

0.366

4.12

9.31

26/0

10/30

0.333

3.75

8.46


 

Recent Updates

Newsletter