Every ring size system in the world describes the same thing — the inside diameter or inside circumference of the ring. Countries just label those measurements differently. To use the chart:
Measure your finger's circumference, or the inside diameter of a ring that already fits (see the methods below).
Find the closest value in the Diameter (mm) or Circumference (mm) column.
Read across that row for your size in US, UK, Europe, Japan and India.
If your measurement sits between two rows, round up to the larger size — a slightly loose ring is far better than one that won't go over your knuckle.
The main ring size systems explained
US & Canada use a numeric scale (3 to 13+), including half sizes.
UK & Australia use letters (A to Z and beyond), with half sizes shown as "½".
Europe (ISO 8653) is the simplest — it's just the inside circumference in millimetres.
Japan uses its own numeric scale from about 1 to 27.
India uses a numeric scale (often 1 to 30) based on circumference.
Quick ways to measure at home
You don't need a jeweler to get close:
String / paper: wrap a strip around the base of your finger, mark where it overlaps, measure that length in mm — that's your circumference.
Existing ring: measure the inside diameter of a ring that fits, edge to edge, in mm.
Measure at the end of the day, when fingers are largest.
Avoid measuring when your hands are cold — fingers shrink.
For wide bands (6 mm+), go up about half a size.
Account for your knuckle — the ring must slide over it.
Note: Conversions are approximate and rounded to the nearest standard size; systems vary slightly between manufacturers. For an expensive or made-to-order ring, confirm with a jeweler.
In the US, the most common women's ring size is between 6 and 6.5, and the most common men's size is between 9 and 10. These map to an inside diameter of roughly 16.5 mm and 19 mm respectively.
How do I read the ring size chart?
Find your inside diameter or circumference in millimetres in the chart, then read across the row to see the matching US, UK, Europe, Japan and India size. If your measurement falls between two rows, choose the larger size.
Is US size the same as UK size?
No. The US uses numbers (e.g. 7), while the UK and Australia use letters (e.g. N½). Use the chart to convert between them — a US 7 is about a UK N½.
How is European ring size measured?
European (ISO 8653) ring size is simply the inside circumference of the ring in millimetres. So an EU size 54 means a 54 mm inside circumference.
Does this chart store my data?
No. This is a static reference chart — nothing is entered, uploaded or saved.