I get frequent emails from customers looking to make a chain from our site using jump rings larger or smaller than those in the instructions. Aspect Ratio is the Ratio (value) between a jump rings wire thickness or gauge (GA) and its Inside Diameter (I.D). Aspect Ratio is sometimes shared by chain maille artists. They take their favorite chain and attempt to make it in different I.D. jump ring sizes until they get, what they consider the perfect chain. Instead of stating that the chain works in 16ga 4.5, they notate the A.R. allowing for the chain to be constructed using different size jump rings. This allows the next artist to build a lighter version using thinner gauge jump rings or a bolder version using thicker gauge jump rings and still maintain the structure of the chain.
The most popular request for aspect ratio is the Byzantine Chain (A.R. 3.5). Here is a quick chart for alternative sizes in jump rings. For those who have a thirst for knowledge, continue down to calculating Aspect Ratio.
Here are 5 formulas for basic byzantine:
22ga (0.6mm) x AR (3.5) = ID 2.1 (22ga 2.0mm ID)
20ga (0.8mm) x AR (3.5) = ID 2.8 (20ga 3.0mm ID)
18ga (1.0mm) x AR (3.5) = ID 3.5 (18ga 3.5mm ID)
16ga (1.3mm) x AR (3.5) = ID 4.5 (16ga 4.5mm ID)
14ga (1.6mm) x AR (3.5) = ID 5.6 (14ga 5.5mm ID)
How to Calculate the correct jump ring size using A.R. (Aspect Ratio)
1. We cannot calculate AR using gauge, especially since there is no one wire measurement standard. We use the A.W.G. American Wire Gauge. Be sure to pay attention between A.W.G and British S.W.G as the values are different.
3. When you multiply your favorite wire thickness (converted to mm) with the Aspect Ratio, you will get your target Inside Diameter. NOTE: Just because you get 3.8746752 mm ID, don't get bent when we don't have that size. There is some leeway, generally I round up to the nearest half millimeter and try a 4.0mm ID. But I am just as willing to try 3.5mm ID if I think the results will give me a superior outcome.
Example: If your like standard byzantine, but you want a thicker ring like 16ga. You look up 16ga in the AWG chart which equals 1.291mm in thickness. The Aspect Ratio for Byzantine is 3.5. Multiply (gauge)1.291 mm X (A.R.)3.5 = 4.5185 mm I.D. I round down to 4.5mm ID.
Note: That byzantine has an A.R. of 3.2 minimal to 3.5 standard.