Ring Size Chart
Find and convert ring sizes across US, UK, EU, and Japanese systems. All sizes include diameter and circumference in millimeters.
What ring size do I need?
Ring size is determined by the inside diameter or circumference of the ring. Use the chart below to convert between US, UK, EU, and Japanese sizes, or search a known size to find the matching millimeter measurements.
US size 6
UK L / EU 51 / JP 12
16.5 mm diameter, 51.8 mm circumference
US size 7
UK N / EU 54 / JP 14
17.3 mm diameter, 54.4 mm circumference
US size 8
UK P / EU 57 / JP 16
18.1 mm diameter, 57.0 mm circumference
US size 10
UK T / EU 62 / JP 21
19.8 mm diameter, 62.1 mm circumference
International Ring Size Conversion Table
Search or scroll to find your ring size. All measurements follow ISO 8653 standards.
| US | UK | EU | JP | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14.0 | 44.0 |
| 3.5 | G | 45 | 5 | 14.4 | 45.2 |
| 4 | H | 46 | 7 | 14.8 | 46.5 |
| 4.5 | I | 48 | 8 | 15.2 | 47.8 |
| 5 | J | 49 | 9 | 15.7 | 49.3 |
| 5.5 | K | 50 | 10 | 16.0 | 50.3 |
| 6 | L | 51 | 12 | 16.5 | 51.8 |
| 6.5 | M | 52 | 13 | 16.9 | 53.1 |
| 7 | N | 54 | 14 | 17.3 | 54.4 |
| 7.5 | O | 55 | 15 | 17.7 | 55.7 |
| 8 | P | 57 | 16 | 18.1 | 57.0 |
| 8.5 | Q | 58 | 17 | 18.5 | 58.3 |
| 9 | R | 59 | 19 | 19.0 | 59.5 |
| 9.5 | S | 60 | 20 | 19.4 | 60.8 |
| 10 | T | 62 | 21 | 19.8 | 62.1 |
| 10.5 | U | 63 | 22 | 20.2 | 63.4 |
| 11 | V | 64 | 23 | 20.6 | 64.6 |
| 11.5 | W | 65 | 24 | 21.0 | 65.9 |
| 12 | X | 66 | 25 | 21.4 | 67.2 |
| 12.5 | Y | 68 | 26 | 21.8 | 68.5 |
| 13 | Z | 69 | 27 | 22.2 | 69.7 |
| 13.5 | Z+½ | 70 | 28 | 22.6 | 71.0 |
| 14 | Z+1 | 71 | 29 | 23.0 | 72.3 |
| 14.5 | Z+1½ | 73 | 30 | 23.4 | 73.6 |
| 15 | Z+2 | 74 | 31 | 23.8 | 74.8 |
Ring Sizing Systems Explained
US & Canada
Numerical scale from 3 to 15 with half sizes. The most widely used system in North America. Each whole size increment equals approximately 0.8 mm in diameter.
UK & Australia
Alphabetical scale from A to Z, then Z+1, Z+2, etc. Used in the United Kingdom, Australia, New Zealand, Ireland, and South Africa.
European (EU)
Based on the inner circumference in millimeters, following the ISO 8653 standard. Used across most of continental Europe. Simple and precise.
Japanese (JP)
Numerical system used in Japan. Sizes typically range from 1 to 30+. Based on the inner circumference, similar to the European system but with different numbering.
Ring Size FAQ
How do I use a ring size chart?
Find the ring size system you already know, then read across the row to see the equivalent US, UK, EU, and Japanese sizes plus the inner diameter and circumference in millimeters.
What is a US size 7 ring in UK and EU sizes?
A US size 7 ring is approximately UK size N, EU size 54, Japanese size 14, 17.3 mm inner diameter, and 54.4 mm inner circumference.
Is ring size based on diameter or circumference?
Ring size systems use the inside diameter, inside circumference, or a regional numbering scale. The chart shows both diameter and circumference in millimeters so you can compare systems accurately.
Should I size up or down if I am between ring sizes?
If you are between sizes, size up for comfort, especially for wide bands. Rings wider than 6 mm often need about a half size larger than a narrow band.
Ring Sizing Tips
Measure at the end of the day when your fingers are at their largest. Fingers swell throughout the day and in warm weather.
Wide bands need a larger size. Rings wider than 6mm typically require going up half a size for comfort.
Consider your knuckle. If your knuckle is much larger than the base of your finger, size for the knuckle and consider a comfort-fit band.
When between sizes, go up. A slightly loose ring is more comfortable than one that's too tight.
Measure multiple times. Take 3-4 measurements on different days to account for normal size fluctuations.