The South Sea PearlOpen jewellery tools

International size converter

One measurement. Four ring-size systems.

Measure an existing ring or enter a known size to compare US/Canada, UK/Australia, ISO/EU and Japanese sizing.

1 min to useFree foreverNo account needed
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International converter

Find the closest size

17.4 mm
Match the inner edge to your ring
US / Canada7UK / AustraliaN½ISO / EU54.5Japan14
Inner diameter 17.35 mmInner circumference 54.5 mm

Closest standard size only. Confirm wide bands and valuable purchases with the maker.

Built to answerring size calculator · international ring size converterBuilt on inner circumference—the international reference.

Transparent by design

A useful answer, with its limits left visible.

01

Inputs you can inspect

Every output changes in response to visible controls. No hidden “AI score” and no email gate.

02

Source-led language

International ring size is designated from inner circumference in millimetres.

ISO 8653:2016
03

Decision, not diagnosis

The result helps you ask better questions. It does not replace a physical inspection, laboratory report or final fit check.

For editors, educators & jewellers

Put this tool on your site.

It is responsive, has no login and embedded mode loads no analytics script. The generated credit uses a branded, qualified link so the embed stays publisher-safe.

  • Works in any CMS that accepts an iframe
  • Light and dark modes
  • Editorial reviews may link in their own words
Theme
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  <iframe
    src="https://your-tool-domain.example/embed/ring-size-converter?theme=light"
    title="Ring Size Converter by The South Sea Pearl"
    loading="lazy"
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    sandbox="allow-scripts allow-same-origin allow-popups"
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  <p style="margin:8px 4px;font:12px/1.4 system-ui;color:#5f6966">
    Free tool by <a href="https://your-tool-domain.example/tools/ring-size-converter" rel="nofollow noopener" target="_blank">The South Sea Pearl</a>
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Plain-language answers

Questions this tool should settle.

Should I measure the inside or outside of a ring?

Measure the inside diameter at the widest point, without including the metal. ISO ring-size designation is based on inner circumference in millimetres.

Why do conversion charts disagree?

Regional systems use different increments and not every size maps exactly. Manufacturing tolerances, band width and finger conditions also affect fit, so conversions are approximate.

Does a wide band need a different size?

Often, yes. Wide bands can feel tighter than narrow ones. Confirm the final fit with the specific jeweller before ordering.

From learning to choosing

See these ideas in real pearls.

Explore pieces selected by pearl type, colour and size at The South Sea Pearl.

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