Ring Size Converter

Topsy Jewels — Tools

Ring Size Converter

Enter any measurement — diameter, circumference, US size, or UK size — and instantly see your equivalent in every international sizing system.

Convert from Inner Diameter

Measure the inside width of a ring that already fits you — straight across the inside opening — using a ruler or digital calipers. Enter the measurement in millimetres below.

mm
Please enter a diameter between 12 mm and 26 mm.
Your Ring Size — All Systems
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Sizes shown are the closest match from our chart. If you are between sizes, always choose the larger size for comfort.
Where your size falls — US 3 to US 13.5
US 3 (smallest)US 13.5 (largest)
Quick Reference Table

Click any row to highlight it. Your converted size will be highlighted automatically after converting.

US Diameter Circumference UK / AU EU Japan Swiss

Need the full Size Guide?

Step-by-step measurement methods, expert tips, average sizes, and FAQs — all in one place.

View Size Guide →