Ring Size Chart
This ring size chart lists every US size from 3 to 13, in half steps, with the inner diameter and circumference in millimeters. It also shows the matching UK, EU, and Japan sizes so you can convert in one place.
| US | Dia mm | Circ mm | UK | EU | JP |
|---|---|---|---|---|---|
| 3 | 14.1 | 44.2 | F | 44 | 4 |
| 3.5 | 14.5 | 45.5 | G | 45 | 5 |
| 4 | 14.9 | 46.8 | H | 47 | 7 |
| 4.5 | 15.3 | 48.0 | I | 48 | 8 |
| 5 | 15.7 | 49.3 | J.5 | 49 | 9 |
| 5.5 | 16.1 | 50.6 | K.5 | 51 | 10 |
| 6 | 16.5 | 51.9 | L.5 | 52 | 11 |
| 6.5 | 16.9 | 53.1 | M.5 | 53 | 12 |
| 7 | 17.3 | 54.4 | N.5 | 54 | 13 |
| 7.5 | 17.7 | 55.7 | O.5 | 56 | 15 |
| 8 | 18.1 | 57.0 | P.5 | 57 | 16 |
| 8.5 | 18.5 | 58.2 | Q.5 | 58 | 17 |
| 9 | 18.9 | 59.5 | R.5 | 60 | 18 |
| 9.5 | 19.4 | 60.8 | S.5 | 61 | 19 |
| 10 | 19.8 | 62.1 | T.5 | 62 | 20 |
| 10.5 | 20.2 | 63.4 | U.5 | 63 | 22 |
| 11 | 20.6 | 64.6 | V.5 | 65 | 23 |
| 11.5 | 21.0 | 65.9 | W.5 | 66 | 24 |
| 12 | 21.4 | 67.2 | Y | 67 | 25 |
| 12.5 | 21.8 | 68.5 | Z | 68 | 26 |
| 13 | 22.2 | 69.7 | Z.5 | 70 | 27 |
Columns: US is the US and Canada number, Dia and Circ are the inside diameter and circumference in millimeters, UK is the UK and Australia letter, EU is the ISO size, JP is the Japan number. Sizes follow the US standard, where inside circumference equals 36.54 plus 2.55 times the size in mm (ISO 8653). The other systems are matched by inside circumference.
How to use this chart
If you have a measurement in millimeters, find it in the diameter or circumference column and read the US size on that row. If you have a ring you own, measure the inside across the widest point to get the diameter, then match it. The reading lands between two rows often, so round to the nearest and size up if the band is wide.
To measure from scratch, the printable ring sizer turns these numbers into real-size circles and a wrap strip, with a built-in check so the print is true to scale. For the step-by-step, read how to measure ring size at home.
US to UK and EU at a glance
The three systems measure the same finger, just on different scales. US uses a number, UK uses a letter, and the EU number is simply the inside circumference in millimeters rounded off. So an EU 54 ring has a 54 mm inside circumference, which is a US 7. When you convert, always go through the millimeter measurement rather than guessing, since the letter and number scales do not line up evenly.
Frequently asked questions
How is US ring size related to millimeters?
US ring size is a number, not a length. Each whole size adds about 2.55 mm of inside circumference, which is about 0.81 mm of inside diameter. The chart above does the conversion for you, so you can match a measured diameter or circumference straight to a US size.
How do I convert a UK ring size to US?
Find the US row in the chart and read across to the UK letter. UK sizes step in half letters, so US 7 is close to UK N and a half, and US 9 is near UK R and a half. The chart pairs them by inside circumference, which is the measurement both systems are built on.
What is the average ring size?
For women the most common engagement-ring sizes are US 6 to 7, and for men US 9 to 10. These are a starting point, not a substitute for measuring, since finger size varies a lot between people and even between hands.
Can I print this chart?
Yes, and you should print at 100% scale if you plan to lay a ring on it. Even better, use the printable ring sizer, which has the chart built into true-scale circles plus a wrap strip and a scale check on one page.