Moved from the web site and updated.
Jump the next 3 paragraphs if you are a technophobe or just bored with the detail :)
Watch Sizes are specified by the diameter of the movement where it fits in the case, there are now two common measures, “Lancashire” for English and American watches and “Ligne” for Swiss.
Lancashire starts at size 0
which is 1 5/30inch increasing by 1/30 inch per size. So the popular men’s size
16 is 1.7 inch and size 18 1.77inch but it is quite possible for a watch case
to make a smaller movement look several sizes bigger although the dial remains
the same size.
|An unrestored S12 fusee movement|
with its carrier and oversized dial.
It was also common practice to mount 19th century English movements onto the back of a carrier two sizes bigger, the carrier attached to the larger size case and had the larger size dial on the other side so that it was indistinguishable from the larger size watch without opening it up.
Where quoted I normally use the nearest equivalent “Lancashire” size for Swiss watches.
As a rough guide the following table shows the approximate diameter of the watch for "normally" cased American and Swiss movements, some may be rather larger but a few can be smaller.
- S14 4.9 – 5.0 cm
- S16 5.0 – 5.2 cm
- S18 5.4 cm+
Movements of size 12 and below and size 18 and above can vary significantly in size when cased up, so on the web site I normally give the dimensions for each watch as part of the description.Here are some general guidelines on what each size of watch is best suited for, clearly there is room for variation here particularly for ladies if they are wearing a waistcoat or carry the watch in a handbag. And although a Fob watch is normally defined as one below about size 8 it is really only limited by the size of the fob pocket!
|A Ladies size 6 Waltham, heavily patterned cases are|
frequently used on these smaller watches.
Ladies watches only, suitable for wearing on a neck chain as a pendant (but be careful not to swing it around too much and bash it on something) or as a brooch with a suitable attachment.
Ladies, as size 0 or as a fob watch. Men, as a fob watch.
|A size 12 Rotherham although tightly cased |
for a pin set watch it is still 1.9" / 4.7cm
in diameter, about the same an American size 14
Getting rather large to be a Fob watch but some American size 12s will be OK used as above. Many old size 12 movements are put into size 14 cases with the use of a carrier as described above.
English pin set size 12s make a good sized mans watch.
Size 14 & 16
|A size 16 hunter in a New Old Stock Dennison |
case. A Hunter will always be a little bigger
than an open faced watch due to the space
taken by the bezel and lid.
A common size in the nineteenth century in all forms, this became the “standard” man’s size for keyless watches in the twentieth century, these are generally quite slim so do not distort pockets as much as earlier key set watches.
This was the smallest size that could be certified as a “Railway” watch in the USA (beware of this term! Originally it defined an accurate and reliable timepiece suitable for controlling railroad traffic in the US, later it was picked up as a marketing ploy and appears on some really awful Swiss watches – you have been warned!).
|A tightly cased Waltham 1892 railroad watch.|
Originally the watch to go for to show status and now very popular with collectors, particular of North American watches and it is frequently said the bigger the better. Some very fine watches were made in the calibre.
Size 20 & 22
As for Size 18 but really showing off, not that common and most in UK are key set from the front and made in the 1890’s and very early in the new century.
Are really too big to carry around but frequently would have had a special stand to convert them into something you could use as a travelling clock.