Ring Size Converter.
Find your ring size in US, UK and EU formats. Enter your finger's diameter or circumference in mm to find your size.
Or select from the chart
Your Ring Sizes
Complete Ring Size Chart
| US / Canada | UK / AU | EU / German | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|
| 4 | H | 46.5 | 14.8 mm | 46.5 mm |
| 4.5 | I | 47.8 | 15.2 mm | 47.8 mm |
| 5 | J½ | 49 | 15.6 mm | 49.0 mm |
| 5.5 | K½ | 50.3 | 16.0 mm | 50.3 mm |
| 6 | L½ | 51.5 | 16.4 mm | 51.5 mm |
| 6.5 | M½ | 52.8 | 16.8 mm | 52.8 mm |
| 7 | N½ | 54 | 17.2 mm | 54.0 mm |
| 7.5 | O½ | 55.3 | 17.6 mm | 55.3 mm |
| 8 | P½ | 56.6 | 18.0 mm | 56.6 mm |
| 8.5 | Q½ | 57.8 | 18.4 mm | 57.8 mm |
| 9 | R½ | 59 | 18.8 mm | 59.0 mm |
| 9.5 | S½ | 60.3 | 19.2 mm | 60.3 mm |
| 10 | T½ | 61.6 | 19.6 mm | 61.6 mm |
| 10.5 | U½ | 62.8 | 20.0 mm | 62.8 mm |
| 11 | V½ | 64 | 20.4 mm | 64.0 mm |
| 11.5 | W½ | 65.3 | 20.8 mm | 65.3 mm |
| 12 | X½ | 66.6 | 21.2 mm | 66.6 mm |
Related Tools
How to find your ring size
- Wrap a strip of paper around the base of your finger and mark where it overlaps.
- Measure that length in millimetres — that is your circumference. Divide it by π (3.14159) if you need the diameter instead; both inputs above accept either.
- Find the closest circumference in the table and read across for US, UK and EU sizes.
- Measure at the end of the day and on a warm hand; fingers change size by up to half a size.
Frequently Asked Questions
What does a ring size mean in millimetres?
Ring sizes describe the inside of the ring. A US 7 has an inner diameter of 17.2 mm and an inner circumference of 54.0 mm. That is UK N½ and EU 54, since EU sizes are simply the circumference in millimetres.
How do I measure my ring size at home?
Wrap a strip of paper round the base of your finger, mark where it overlaps, and measure the length in millimetres: that is the circumference. Or measure the inside diameter of a ring that already fits. Measure at the end of the day, when fingers are largest.
How do US, UK and EU ring sizes compare?
US sizes are numbers, UK sizes are letters, and EU sizes are the inner circumference in millimetres. For example, US 6 = UK L½ = EU 51.5; US 7 = UK N½ = EU 54; US 8 = UK P½ = EU 56.6. Each half US size is about 1.3 mm of circumference.
What if I am between two ring sizes?
Choose the larger size, especially for a wide band, which feels tighter than a thin one of the same size. The ring has to pass over the knuckle, and fingers swell in heat and later in the day.
Sources
- ISO 8653:2016, ring sizes by inner circumference in millimetres