Sizing Guide

World Ring Size Comparison

International ring sizing reference

One measurement, every system

Every ring sizing system in the world is describing the same physical thing — the inside circumference of the ring — just labeled on a different scale. This table cross-references the major systems against that single shared measurement, so you can look up a size in one country and find its match anywhere else.

US / CanadaUK / AU / NZJapan / ChinaEU / ISO (mm)Diameter (mm)
US 3UK F444.2 mm14.1 mm
US 3.5UK G545.5 mm14.5 mm
US 4UK H746.8 mm14.9 mm
US 4.5UK I848.0 mm15.3 mm
US 5UK J949.3 mm15.7 mm
US 5.5UK K1050.6 mm16.1 mm
US 6UK L1251.9 mm16.5 mm
US 6.5UK M1353.1 mm16.9 mm
US 7UK N1454.4 mm17.3 mm
US 7.5UK O1555.7 mm17.7 mm
US 8UK P1757.0 mm18.1 mm
US 8.5UK Q1858.3 mm18.5 mm
US 9UK R1959.5 mm18.9 mm
US 9.5UK S2060.8 mm19.3 mm
US 10UK T2262.1 mm19.7 mm
US 10.5UK U2363.4 mm20.1 mm
US 11UK V2464.6 mm20.5 mm
US 11.5UK W2665.9 mm20.9 mm
US 12UK X2767.2 mm21.3 mm
US 12.5UK Y2868.5 mm21.7 mm
US 13UK Z2969.7 mm22.1 mm

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Regional notes worth knowing

India commonly follows the same letter-based scale as the UK, though some jewelers there also use the US numeric scale — it's worth confirming which one a specific retailer means. China and much of the rest of Asia generally align closely with Japan's numeric scale, but not always exactly, so local confirmation matters for anything you can't easily resize. Switzerland and other parts of continental Europe sometimes use sizing conventions distinct from the standard EU/ISO circumference figure shown here — when in doubt, ask the jeweler which specific scale their listed number refers to.

Why one universal chart doesn't quite exist

There's no single global governing body that unifies ring sizing the way there is for, say, shoe sizing under ISO standards worldwide. Instead, each region standardized its own scale independently, and ISO 8653:2016 exists as a reference point that most — but not all — national systems can be cross-checked against. That's the gap this chart is built to close.

Figures here are standard references cross-checked against inside circumference. Normal finger-size fluctuation, band width, and comfort-fit inner edges can all shift the ideal size slightly, so confirm with a local jeweler's gauge before an expensive or hard-to-resize purchase.