What is Aspect Ration (AR) all about?  Here's a quick and simple document that explains it all....  

Aspect Ratio is easy!  Keep repeating that over and over and over. 

Aspect Ratio is very useful, especially for chainmakers.  Aspect Ratio (AR) is how the diameter of wire in millimeters relates to the internal diameter of the ring.  (Clear as mud, right?)

AR = inside diameter divided by the wire diameter

Simple !  How do we use it?

If I am making a Byzantine chain and the AR is 3.5, then I know I can figure out what the internal diameter is for any wire gauge size I want to use.  This allows me the flexibility to change wire gauges and make heavier or more delicate chains..... so to make a Byzantine in various gauges...

• 3.5 = x/y  where x is the internal diameter of the ring and y is the diameter of the wire.... (looking like algebra, eh?) ..... OR...
• 3.5 = ID/wire diameter

Rearrange the equation

• AR times y = (x divided by y) times y (to cancel the y from the right side of the equation)
• AR times y = x   (substitute 3.5 which is the aspect ratio for the Byzantine)
• 3.5 times y = x    OR
• AR times wire diameter = ring inside diameter.

16 gauge = 1.3mm;  18 gauge = 1.0mm;  20 gauge = 0.8mm

• 16 gauge wire size      3.5 times 1.3mm = 4.55mm
• 18 gauge wire size     3.5 times 1.0mm = 3.50mm
• 20 gauge wire size    3.5 times 0.8mm = 2.275mm

Now you have the internal diameters but what if the rings don't come in 2.275mm ID?  Round up to the next ring size.  Especially for a tight weave like the Byzantine, if you round down, your weave may be too tight.  For a weave that is looser, like a 3 in 3 or European 4 in 1, you could round down to 2.0mm ID in 22 gauge.  Having said that, 4.55mm ID for 16 ga wire is close enough to 4.5mm that it will work splendidly for the Byzantine.