Free tool
Ring size chart & converter
Ring sizes are set by the inside of the ring. US sizes are numbers, UK sizes are letters, and European sizes are the inside circumference in millimetres. Find a size in the chart below to read it in every system, or print the sizer at the bottom. All charts are approximate, so ask a jeweller to check the size before you buy.
| US | UK | EU | Japan | Inside diameter | Inside circumference |
|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14.1 mm | 44.3 mm |
| 3½ | G | 46 | 6 | 14.5 mm | 45.6 mm |
| 4 | H½ | 47 | 7 | 14.9 mm | 46.8 mm |
| 4½ | I½ | 48 | 8 | 15.3 mm | 48.1 mm |
| 5 | J½ | 49 | 9 | 15.7 mm | 49.3 mm |
| 5½ | L | 51 | 11 | 16.1 mm | 50.6 mm |
| 6 | M | 52 | 12 | 16.5 mm | 51.8 mm |
| 6½ | N | 53 | 13 | 16.9 mm | 53.1 mm |
| 7 | O | 54 | 14 | 17.3 mm | 54.3 mm |
| 7½ | P | 56 | 16 | 17.7 mm | 55.6 mm |
| 8 | Q | 57 | 17 | 18.1 mm | 56.9 mm |
| 8½ | Q½ | 58 | 18 | 18.5 mm | 58.1 mm |
| 9 | R½ | 59 | 19 | 18.9 mm | 59.4 mm |
| 9½ | S½ | 61 | 21 | 19.4 mm | 60.9 mm |
| 10 | T½ | 62 | 22 | 19.8 mm | 62.2 mm |
| 10½ | U½ | 63 | 23 | 20.2 mm | 63.5 mm |
| 11 | V½ | 65 | 25 | 20.6 mm | 64.7 mm |
| 11½ | W½ | 66 | 26 | 21.0 mm | 66.0 mm |
| 12 | X½ | 67 | 27 | 21.4 mm | 67.2 mm |
| 12½ | Y | 68 | 28 | 21.8 mm | 68.5 mm |
| 13 | Z | 70 | 30 | 22.2 mm | 69.7 mm |
Sizes are approximate. A wide ring band and swollen fingers both change the result. Ask a jeweller to check the size before you buy.
Printable ring sizer
Print at 100% (“Actual size”), never “Fit to page”. Then measure the bar with a real ruler: if it isn’t exactly 50 mm, the circles are the wrong size.
The Measure App · Ring sizer · Lay a ring that fits on the circles. Your size is the circle that matches the ring’s inside edge.
This bar must measure exactly 50 mm.
14.1 mm
14.9 mm
15.7 mm
16.5 mm
17.3 mm
18.1 mm
18.9 mm
19.8 mm
20.6 mm
21.4 mm
22.2 mm
Approximate. Ask a jeweller to check the size before you buy.
How to use the chart
- Pick the system you know and choose your size. The matching row lights up.
- Or measure the inside of a ring that fits, straight across, in millimetres, and type it in. The chart picks the nearest row.
- Read your size in any other system along that row.
Where these numbers come from
The chart uses the same table as the ring sizer in The Measure App. European sizes are the inside circumference in millimetres, the definition used by the 1986 edition of ISO 8653 (ISO) (the current edition is ISO 8653:2016 (ISO)). Japanese sizes here count one size for each millimetre of circumference above 40 mm, which is how the app works them out. US and UK sizes come from the app’s table; other jewellers’ charts can differ by a fraction of a size.
Before you buy
Home sizing is a starting point. GIA advises asking a jeweller to measure your ring size, and notes that fingers shrink in the cold and swell in the heat (GIA). Jewelers of America also recommends getting your fingers professionally sized (Jewelers of America). Our guide on how to measure ring size at home covers the methods.
Questions
What is the most common ring size?
We don’t publish one: we haven’t found an official source for it, and fingers vary a lot. A jeweller can size you in a few minutes.
How do I convert a UK ring size to a US size?
Find the UK letter in the chart and read across to the US column. For example, UK O is US 7 in this chart. Different jewellers’ charts can differ by a fraction of a size, so ask the seller which chart they use.
Is the printable ring sizer accurate?
Only if it prints at exactly 100%. Check the 50 mm bar with a real ruler before you use it. Even then, home sizing is approximate: GIA advises asking a jeweller to measure ring size (GIA).
Why does my ring size change?
Fingers change size. GIA notes that fingers shrink in the cold and swell in the heat (GIA). A jeweller can allow for that when sizing you.