Ring Size Converter

Enter a size you already know — in any system — and get the full equivalents across US, UK/Ireland, EU, Japan, plus the physical diameter and inside circumference in millimetres. Everything runs in your browser; nothing is sent anywhere.

Convert a Ring Size

For UK enter a letter like L½, Q or Z+1. Everything else is a number.
US / Canada
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UK / Ireland
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EU / ISO
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Japan
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Diameter
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Circumference
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How to measure at home: wrap a strip of paper or a piece of string around the base of the finger, mark where it overlaps, and measure the length in millimetres — that is the inside circumference. Measure at the end of the day when fingers are largest, and size up if a knuckle is wide. A jeweller’s sizing gauge is always the most accurate.

Selling rings online?

Lustriel gives Stuller retailers a calm, step-by-step ring configurator with exact media and live pricing — so customers choose the right ring, and the right size, with confidence.

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