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How to Size Pocket Watches

Most American pocket watches, except for early E. Howard movements, use the Lancashire system, which measures the diameter of the watch dial in millimeters. Millimeters are then converted to approximate inches to correspond to Lancashire system sizes. There are different sized pocket watches for men and women. While the measurement eventually becomes an approximation (due to the conversion), it is still a good idea to measure as precisely as possible with a set of calipers.

Things You'll Need

Calipers

Instructions

- 1
  Remove the bezel with the crystal. The bezel is the glass side of the watch case. Different types of bezels include snap back cases, crew back and bezel cases, hinge back with bezel cases and swing-out cases. Snap back cases snap on and off like food container lids, some screw on and off, some have a hinged case and bezel and some have a swing-out case, which is recognizable by a fine line separating the bezel from the body of the case.
- 2
  Measure the distance across the center of the dial from edge to edge.
- 3
  Find the corresponding size. The most common sizes for men (from smallest to largest) are 12 (approximately 1-9/16 inches across), 14, 16, 18 (approximately 1-3/4 inches across) and 20. The most common sizes for women (from largest to smallest) are 8 (approximately 1-7/16 inches across), 6, 0 (approximately 1-1/8 inches across) and 000. There is approximately 1/16 of an inch between adjacent sizes.

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