USA Ring Sizes Conversion Table – MM : Inches

We have created the ring size conversion table below so you can convert ring sizes from mm (millimetres) to inches to see what your USA ring size is.

Determine your ring size based on finger measurement: In Method 1 use a flexible measuring tape – a dressmaking tape is perfect – to measure around your finger. If you have a tape in inches that’s ideal as you can match to your USA size easily. If your tape is in mm only simply match back across the row to see the USA equivalent size which is in the first column. Using Method 2 you will be matching from a ring that you already know fits you correctly by measuring its internal diameter. See ring sizing tips >>

Method 1 – Circumference
Measure the circumference around your ring finger (exactly where the ring is supposed to be located). Do not tighten the measuring tape too much, it is supposed to sit quite loose around your finger. Then look up your measurement in the ring size chart below and match to the USA sizing in the far left column. Find your measurement in the column “Circumference” and then find the corresponding ring size (“Ring size” column).

Method 2 – Diameter
Find ring size based on a ring measurement that fits you: Use a ruler or measuring tape (inches) to carefully measure the inside diameter of a ring (edge to edge). Make sure to measure where the diameter is largest (center). Look up your measurement in the ring size chart below (“Diameter” column). Find the corresponding ring size (“Ring size” column) – and you are ready to go shopping for rings!

See international ring sizing systems >>

USA Ring Sizes