Millimetres to EU ring size converter
This is the simplest conversion of all: under ISO 8653 the EU ring size equals the inner circumference in millimetres. If your ring measures 54 mm around the inside, it is an EU 54. Enter a circumference (or a diameter to convert) below.
Quick answer
A mm 54.4 is 54 in EU (about 54.4 mm inner circumference). Use the converter for your exact size, or the chart below for the full range.
Between two sizes? Size up for a comfortable fit, see how to measure accurately.
mm → EU at a glance
- 46.7 mm = 47
- 49.3 mm = 49
- 51.8 mm = 52
- 54.4 mm = 54
- 56.9 mm = 57
- 59.5 mm = 59
- 62.0 mm = 62
- 64.6 mm = 65
mm to EU ring size chart
| mmCircumference | EUEU / ISO | mmDiameter |
|---|---|---|
| 46.7 | 47 | 14.9 |
| 48.0 | 48 | 15.3 |
| 49.3 | 49 | 15.7 |
| 50.5 | 51 | 16.1 |
| 51.8 | 52 | 16.5 |
| 53.1 | 53 | 16.9 |
| 54.4 | 54 | 17.3 |
| 55.6 | 56 | 17.7 |
| 56.9 | 57 | 18.1 |
| 58.2 | 58 | 18.5 |
| 59.5 | 59 | 18.9 |
| 60.7 | 61 | 19.3 |
| 62.0 | 62 | 19.7 |
| 63.3 | 63 | 20.1 |
| 64.6 | 65 | 20.5 |
| 65.8 | 66 | 21.0 |
| 67.1 | 67 | 21.4 |
Common questions
How do I convert a mm ring size to EU?
Enter your mm size in the converter above and read the EU result, or find your row in the chart below. Every value is calculated from the ring’s inner circumference, so it works in both directions.
What is a mm 54.4 in EU?
A mm 54.4 is 54 in EU. That ring has an inner circumference of about 54.4 mm.
Related conversions
Or see the full ring size chart.