What are Lignes in watches?| Caliber Corner

If you’ve been in the Caliber Corner Community for some time, you’ve seen the word lignes here and there. What does it all mean? What is a lig-nez?!

Lignes is the French word for lines (and pronounced the same way), a unit of measurement for watch movements. Although most watch movements will have the diameters listed in millimeter (mm), you may also see linges listed – especially when dealing with raw movements.

Here is a brief history from Wikipedia:

The ligne or line or Paris line, is a historic unit of length used in France and elsewhere prior to the adoption of the metric system in the late 18th century, and used in various sciences after that time. The loi du 19 frimaire an VIII (Law of 10 December 1799) states that one metre is equal to exactly 443.296 French lines.

Interestingly, in addition to watch movements, the lignes unit of measurement is also used by some button and ribbon manufactures. Here is an explanation about lignes from ETA:

Following a centuries-old tradition, watchmakers use lines rather than millimetres to describe the size of the movement’s diameter. This measurement is generally indicated as a triple apostrophe, so 16 1/2 lines is written as 16 1/2´´´, or 37.22 mm diameter. The line, or Parisian line, is an ancient watchmaking measurement that predates metrification and is a direct descendant of the French pied (foot) measurement used under the Ancien Régime. Each line is equivalent to 2.2558 mm, which is rounded up to 2.26 mm for ease of calculation. In the past the French foot used to correspond to 12 inches measuring 12 lines each.

American watchmakers also had their own measuring system for watch movements, more on that here.

How to Measure Lignes

There are calipers and rulers that are set up for measuring lignes such as this one. If you don’t have a tool, you can convert mm to lignes the old fashioned way:

1 Ligne = 2.25583mm

And conversely 1 mm = 0.4433 ligne.

Representing Lignes

Caliber Corner posts as much information about each movement as possible – including the diameter in lignes and millimeters. When you see three apostrophes (”’) after the number, it’s not a typo. That’s the linges measurement.

Note that many font types and autocorrections can cause the ”’ to display incorrectly. Frustratingly, at the time of this post, the font type on Caliber Corner causes it to look like a quotation next to an apostrophe.

Lignes to mm to Inch Conversion Chart

Lignes	Millimeters	Inches
¼	0.05640	0.0222
½	1.128	0.0444
¾	1.692	0.0666
1	2.255	0.0888
1¼	2.820	0.1111
1½	3.338	0.1332
1¾	3.949	0.1554
2	4.517	0.1776
2¼	5.076	0.1998
2½	5.640	0.2220
2¾	6.204	0.2442
3	6.768	0.2664
3¼	7.332	0.2886
3½	7.895	0.3108
3¾	8.459	0.3330
4	9.023	0.3553
4¼	9.587	0.3775
4½	10.151	0.3997
4¾	10.715	0.4219
calibercorner.com	calibercorner.com	calibercorner.com
5	11.279	0.4441
5¼	11.843	0.4663
5½	12.407	0.4885
5¾	12.971	0.5107
6	13.535	0.5329
6¼	14.099	0.5551
6½	14.663	0.5773
6¾	15.227	0.5995
7	15.791	0.6217
7¼	16.355	0.6439
7½	16.919	0.6661
7¾	17.483	0.6883
8	18.047	0.7105
8¼	18.611	0.7327
8½	19.175	0.7549
8¾	19.739	0.7771
9	20.303	0.7993
9¼	20.867	0.8215
9½	21.430	0.8437
9¾	21.994	0.8659
10	22.558	0.8881
10¼	23.122	0.9103
10½	23.686	0.9325
10¾	24.250	0.9547
11	24.814	0.9770
11¼	25.387	0.9992
11½	25.942	1.0214
11¾	26.506	1.0436
12	27.070	1.0658
12½	28.198	1.1102
12¾	28.762	1.1324
13	29.326	1.1546
13½	30.453	1.1990
14	31.581	1.2434
14¼	32.046	1.2656
14¾	33.273	1.3100
15	33.838	1.3322
calibercorner.com	calibercorner.com	calibercorner.com
15½	34.955	1.3766
15¾	35.529	1.399
16	36.093	1.4210
16¼	36.657	1.4432
16½	37.221	1.4654
17	38.349	1.5098
17¼	38.913	1.5320
17¾	40.041	1.5764
18	40.605	1.5987
18½	41.733	1.6431
18¾	42.297	1.6653
19	42.861	1.6875
19¼	43.425	1.7097
19½	43.989	1.7319
20	45.117	1.7763
21	47.372	1.8651
22	49.628	1.954
23	51.884	2.0427
24	54.140	2.1315
25	56.396	2.2204
26	58.652	2.3092
27	60.907	2.3980
28	63.163	2.4868
29	65.419	2.5756
30	67.675	2.6644