Understanding Pocket Watch Sizes and Gram Weights: A Guide to Measurements

October 26, 2025 - Pro Tip: When creating your appraisal request, include the watch size in your description. Use 16s for size 16. Don't use inches please. Refer to this guide to determine the correct term to use.

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Background

Pocket watches come in various sizes, with terms like 0s, 6s, 8s, 12s, 14s, 16s, and 18s referring to the movement size rather than the case size. This measurement system originated in the 19th century and remains an essential standard for collectors and watch enthusiasts.

History of Pocket Watch Sizing

The pocket watch sizing system is derived from the Lancashire gauge, an English measurement system adapted by American watchmakers. In this system, size "0" was set at 1 inch (25.4 mm), and each increase in size adds approximately 1/30th of an inch (0.85 mm) to the movement’s diameter. This method allows for standardization across different manufacturers.

How to Measure a Pocket Watch ?

Measure the diameter of the watch face (movement), not the outer case. Since cases were often sold separately, collectors must ensure that the movement size matches the correct case.

Common Pocket Watch Sizes and Their Measurements

0s

(1.16 inches / 29.63 mm) – A very small size, commonly used in women's pocket watches and pendant watches.
Open Face 14K - 12 grams
Hunter Closed Face 14K - 18 grams

6s

(1.37 inches / 34.7 mm) – A compact size, often used in smaller dress watches.
Open Face 14K - 16 grams
Hunter Closed Face 14K - 22 grams

8s

(1.43 inches / 36.4 mm) – Slightly larger than 6s, seen in both men's and women's styles.
Open Face 14K - 20 grams
Hunter Closed Face 14K - 30 grams

10s

1.5 inches / 38.1 mm) – One of the most popular sizes for dress pocket watches.
Open Face 14K - 18 grams
Hunter Closed Face 14K - 25 grams

12s

(1.39 inches / 39.8 mm) – One of the most popular sizes for dress pocket watches.
Open Face 14K - 22 grams
Hunter Closed Face 14K - 35 grams

14s

(1.63 inches / 41.5 mm) – Less common but used in select vintage models.
Open Face 14K - 26 grams
Hunter Closed Face 14K - 40 grams

16s

(1.7 inches / 43.8 mm) – The standard size for railroad-grade pocket watches, prized for accuracy and durability.
Open Face 14K - 30 grams
Hunter Closed Face 14K - 50 grams

18s

(1.76 inches / 44.8 mm) – A large and sturdy size, widely used in 19th-century railroad watches.
Open Face 14K - 38 grams
Hunter Closed Face 14K - 60 grams

Pocket Watch Size Conversion Example

To understand how size relates to measurement:
- If the face of a pocket watch measures roughly 1.7 inches (43.8 mm), it's a size 16.
- If the face measures roughly 1.76 inches (44.8 mm), it's a size 18.

Providing the watch size in your appraisal request helps you get an accurate appraisal for your watch.

Get Your Pocket Watch Appraised with iGuide

Do you own a vintage pocket watch and wonder what it’s worth? iGuide offers expert pocket watch appraisals, helping collectors determine the market value of their timepieces. Whether it's a rare railroad watch or a classic dress model, our team provides professional evaluations based on historical data and recent sales. Find out what your pocket watch is worth today with iGuide’s trusted appraisal service!

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