Determining Ring Blank Lengths in millimeters
When designing a ring with a proper and snug fit, you must compensate for the thickness of the ring stock after measuring the ring size. Forcing the outside ends of the ring stock together for soldering compresses the inside circumference, making the ring smaller. As a general rule, the inner surface of the wire will compress, and the outer surface will stretch. The median line that runs down the center of the ring is what we want to plan for. This chart is designed to allow you to look up what you need and plan for your designs without having to take time to figure out the math yourself.
Use this table to determine the length of your Ring Blanks. The first table is a reference to American ring blank sizes in millimeters. So you may need to refer to the tables on the Determining Metal Gauges page first to convert from B. & S. Guage to metric.
Remember, when the metal is bent into a ring shape that the thickness of the metal will affect the length. That is why I am sharing this information. If you have a metal that is between two of the widths in this table, choose the column with the thicker metal and file the end a bit. This fall under the headding of "It is easier to remove a small bit of unwanted metal than to add it"
| Sizes (U.S.A.) | Length (MM) | Metal Thickness in Millimeters | ||||||
|---|---|---|---|---|---|---|---|---|
| 2.0 MM | 1.6 MM | 1.3 MM | 1.0 MM | 0.8 MM | 0.6 MM | 0.5 MM | ||
| 1 | 39.0 | 45.5 | 44.2 | 43.0 | 42.1 | 41.5 | 40.9 | 40.5 |
| 1 1/4 | 39.6 | 46.2 | 44.6 | 43.6 | 42.7 | 42.1 | 41.5 | 41.1 |
| 1 1/2 | 40.2 | 46.9 | 45.2 | 44.3 | 43.3 | 42.7 | 42.1 | 41.8 |
| 1 3/4 | 40.8 | 47.7 | 45.8 | 44.9 | 44.0 | 43.3 | 42.7 | 42.4 |
| 2 | 41.5 | 48.0 | 46.5 | 45.5 | 44.6 | 44.0 | 43.3 | 43.0 |
| 2 1/4 | 42.1 | 48.7 | 47.1 | 46.2 | 45.2 | 44.6 | 44.0 | 43.6 |
| 2 1/2 | 42.7 | 49.3 | 47.7 | 46.8 | 45.8 | 45.2 | 44.6 | 44.3 |
| 2 3/4 | 43.3 | 49.9 | 48.4 | 47.4 | 46.5 | 45.8 | 45.2 | 44.9 |
| 3 | 44.0 | 50.6 | 49.0 | 48.0 | 47.1 | 46.5 | 45.8 | 45.6 |
| 3 1/4 | 44.6 | 51.2 | 49.6 | 48.7 | 47.7 | 47.1 | 46.5 | 46.2 |
| 3 1/2 | 45.2 | 51.8 | 50.2 | 49.3 | 48.4 | 47.7 | 47.1 | 46.8 |
| 3 3/4 | 45.9 | 52.4 | 50.9 | 49.9 | 49.0 | 48.4 | 47.7 | 47.4 |
| 4 | 46.5 | 53.1 | 51.5 | 50.6 | 49.6 | 49.0 | 48.3 | 48.0 |
| 4 1/4 | 47.1 | 53.7 | 52.1 | 51.2 | 50.2 | 49.6 | 49.0 | 48.7 |
| 4 1/2 | 47.8 | 54.3 | 52.8 | 51.8 | 50.9 | 50.2 | 49.6 | 49.3 |
| 4 3/4 | 48.4 | 55.0 | 53.4 | 52.4 | 51.5 | 50.9 | 50.2 | 49.9 |
| 5 | 49.0 | 55.6 | 54.0 | 53.1 | 52.1 | 51.5 | 50.9 | 50.6 |
| 5 1/4 | 49.6 | 56.2 | 54.6 | 53.7 | 52.8 | 52.1 | 51.5 | 51.2 |
| 5 1/2 | 50.3 | 56.8 | 55.3 | 54.3 | 53.4 | 52.7 | 52.1 | 51.8 |
| 5 3/4 | 50.9 | 57.5 | 55.9 | 55.0 | 54.0 | 53.4 | 52.8 | 52.4 |
| 6 | 51.5 | 58.1 | 56.5 | 55.6 | 54.6 | 54.0 | 53.4 | 53.1 |
| 6 1/4 | 52.2 | 58.7 | 57.1 | 56.2 | 55.3 | 54.6 | 54.0 | 53.7 |
| 6 1/2 | 52.8 | 59.3 | 57.8 | 56.8 | 55.9 | 55.3 | 54.6 | 54.3 |
| 6 3/4 | 53.4 | 60.0 | 58.4 | 57.5 | 56.5 | 55.9 | 55.3 | 55.0 |
| 7 | 54.0 | 60.6 | 59.0 | 58.1 | 57.1 | 56.5 | 55.9 | 55.6 |
| 7 1/4 | 54.7 | 61.2 | 59.7 | 58.7 | 57.8 | 57.1 | 56.5 | 56.2 |
| 7 1/2 | 55.3 | 61.9 | 60.3 | 59.3 | 58.4 | 57.8 | 57.1 | 56.8 |
| 7 3/4 | 55.9 | 62.5 | 60.9 | 60.0 | 59.0 | 58.4 | 57.8 | 57.5 |
| 8 | 56.6 | 63.1 | 61.5 | 60.6 | 59.7 | 59.0 | 58.4 | 58.1 |
| 8 1/4 | 57.2 | 63.7 | 62.2 | 61.2 | 60.3 | 59.7 | 59.0 | 58.7 |
| 8 1/2 | 57.8 | 64.4 | 62.8 | 61.9 | 60.9 | 60.3 | 59.7 | 59.3 |
| 8 3/4 | 58.4 | 65.0 | 63.4 | 62.5 | 61.5 | 60.9 | 60.3 | 60.0 |
| 9 | 59.1 | 65.6 | 64.1 | 63.1 | 62.2 | 61.5 | 60.9 | 60.6 |
| 9 1/4 | 59.7 | 66.3 | 64.7 | 63.7 | 62.8 | 62.2 | 61.5 | 61.2 |
| 9 1/2 | 60.3 | 66.9 | 65.3 | 64.4 | 63.4 | 62.8 | 62.2 | 61.9 |
| 9 3/4 | 60.9 | 67.5 | 65.9 | 65.0 | 64.1 | 63.4 | 62.8 | 62.5 |
| 10 | 61.6 | 68.1 | 66.6 | 65.6 | 64.7 | 64.1 | 63.4 | 63.1 |
| 10 1/4 | 62.2 | 68.8 | 67.2 | 66.3 | 65.3 | 64.7 | 64.1 | 63.7 |
| 10 1/2 | 62.8 | 69.4 | 67.8 | 66.9 | 65.9 | 65.3 | 64.7 | 64.4 |
| 10 3/4 | 63.5 | 70.0 | 68.5 | 67.5 | 66.6 | 65.9 | 65.3 | 65.0 |
| 11 | 64.1 | 70.7 | 69.1 | 68.1 | 67.2 | 66.6 | 65.9 | 65.6 |
| 11 1/4 | 64.7 | 71.3 | 69.7 | 68.8 | 67.8 | 67.2 | 66.6 | 66.3 |
| 11 1/2 | 65.3 | 71.9 | 70.3 | 69.4 | 68.5 | 67.8 | 67.2 | 66.9 |
| 11 3/4 | 66.0 | 72.5 | 71.0 | 70.0 | 69.1 | 68.5 | 67.8 | 67.5 |
| 12 | 66.6 | 73.2 | 71.6 | 70.7 | 69.7 | 69.1 | 68.5 | 68.1 |
| 12 1/4 | 67.2 | 73.8 | 72.2 | 71.3 | 70.3 | 69.7 | 69.1 | 68.8 |
| 12 1/2 | 67.9 | 74.4 | 72.8 | 71.9 | 71.0 | 70.3 | 69.7 | 69.4 |
| 12 3/4 | 68.5 | 75.0 | 73.5 | 72.5 | 71.6 | 71.0 | 70.3 | 70.0 |
| 13 | 69.1 | 75.7 | 74.1 | 73.2 | 72.2 | 71.6 | 71.0 | 70.7 |
There are many websites, jewelers books and manuals and jewelry supply catalogs that will have a table like this. Pulled from many different sites, this should be accurate.
Formated so it follows accessibility requirements for the internet.
If you have suggestions for adding to this page, or comments, please email me at the link in the footer below.