Metric ring sizes without making your own? in Discussion Posted December 1, 2012 · Report reply I'd skip the conversion and just shop by AR. As long as you aren't doing something that is very tight close is good enough. You might also want to check Fire mountain if you need to be exact about sizes. They are much more expensive than TRL and most likely dead soft temper, but you can get them in metric if that is the only thing you are worried about.