Ring Size Converter
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Look up equivalent ring sizes across US, UK, EU, JP, and mm circumference.
US ring size
Inner circumference
54.4 mm
US 7 · UK N · EU 54 · JP 13
- US size
- 7
- UK size
- N
- EU size
- 54
- Japan size
- 13
Related calculators
International ring sizes
Ring sizes use different scales by country. US and Canada use a numeric scale (often with half sizes). UK and Australia use letter sizes. EU sizes are based on inner circumference in mm (EU 54 ≈ 54 mm). Japan uses a numbered scale. Matching the closest size across systems helps when buying rings online internationally.
The most accurate fit comes from measuring inner circumference with a ring sizer or caliper on a ring that already fits. Finger size changes with temperature, time of day, and which hand — measure when fingers are warm and at room temperature.
Example: US size 7 corresponds roughly to UK N, EU 54, JP 13, and about 54.4 mm inner circumference. Half sizes fall between chart entries — jewelers can adjust slightly.
Common questions
How do I measure my ring size at home?
Wrap a strip of paper around the finger, mark the overlap, measure length in mm, and divide by π for diameter — or use a printable ring sizer. Professional jewelers offer the most reliable sizing.
Are conversions exact?
Charts map to the nearest standard size. Wide bands and comfort-fit profiles may need a half size up — confirm with the seller's sizing guide.