Ring Size Converter
Convert ring sizes between US numbers, UK letters, EU circumference, inside diameter, and finger circumference in millimeters. Useful when buying rings online, resizing jewelry, or comparing international size charts.
Convert a ring measurement
Choose what you know, enter the value, and the closest sizes update instantly.
US 7 is closest to UK N and EU 54, with an inside diameter of about 17.3 mm.
How to measure for ring size
- Measure the inside diameter of a ring that fits, or wrap a strip of paper around the finger and mark the overlap.
- Use millimeters for the most reliable conversion.
- Measure near the end of the day when fingers are usually slightly larger.
- For wide bands, many jewelers recommend sizing up slightly.
Quick ring size chart
| US | UK | EU | Diameter |
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Ring size conversion FAQ
What is the difference between EU and US ring size?
EU ring size is based on inside circumference in millimeters. US sizes use a numbered scale, usually with half sizes. For example, EU 54 is close to US 7.
Should I round up or down if I am between ring sizes?
For a wider band or warm-weather swelling, rounding up is often safer. For a thin band, the nearest or slightly smaller size may fit better.
Can I use string to measure ring size?
You can use paper or string for an estimate, but it can stretch or sit unevenly. For valuable rings, confirm with a plastic ring sizer or a jeweler.