How to Read This Ring Size Chart
Every row in the chart represents one physical ring size — the same inner diameter and circumference, just labeled differently depending on the sizing system a country or jeweler uses. Find your size in any one column (say, your US size), then read across the row to see the equivalent in every other system. If you already know your ring's diameter or circumference in millimeters, you can match it directly to the "Dia (mm)" or "Circ (mm)" column instead — that's the most reliable way to compare across regions, since diameter and circumference are absolute measurements while letter and number labels are not standardized internationally.
Why the Systems Look So Different
- US & Canada: Numeric scale, roughly 3 to 13 in this chart, increasing in half-size steps.
- UK, Ireland & Australia: Alphabetical scale (this chart runs from F to Z, then continues as Z+1, Z+2 for larger sizes) — a completely different convention from the US numeric scale, so a "size 7" and a "size N" only match up because of the underlying millimeter measurement, not because the labels relate to each other.
- EU: Numeric, but on its own scale (roughly 44 to 70 in this chart) based on inner circumference in millimeters — an EU 54 is not close to a US 54; it corresponds to a US size around 7.
- Japan: Numeric scale that also does not align with US or EU numbers despite looking similar at a glance.
A Note on Half Sizes and Fit
The physical difference between adjacent sizes in this chart is small — often well under half a millimeter of diameter — so if your measurement falls between two rows, either size can work depending on the ring's width and your finger's shape. Wider bands generally need to size up slightly compared to thin bands at the same finger measurement, since more surface area contacts the widest part of the knuckle.