About RingSizeConvert.com

RingSizeConvert.com is an independently run, free reference for converting and understanding ring sizes across the US/Canada, UK/Australia, EU, Germany, Japan, and several India-specific jewelry brand systems. It isn't affiliated with any jeweler, ring brand, or sizing-tool manufacturer named on the site. There are no accounts, no paywalls, and no e-commerce — just calculators, charts, and guides.

The core conversion table is built from published sizing standards and cross-checked across multiple independent sources — including the definitional relationships behind the US/Canada scale (inner diameter step size), the UK/Ireland/Australia/NZ/South Africa scale (inner circumference per letter), the EU/ISO scale (size number equals inner circumference in millimeters), and the Japan/East-Asia diameter-based scale — plus working examples from real jewelry retailers used to confirm the formulas rather than rely on a single source. Where sources disagreed or a system's numbers don't follow a strict linear formula, that's called out rather than smoothed over: for example, the general "India" sizing column on the international chart is intentionally left unsupported because it isn't a single, verifiable national standard — instead, the site's India-specific pages document sizes for named jewelry brands individually, each checked against that brand's own published size guide.

Brand- or country-specific charts sourced from a single external retailer or brand (such as the Oura, Gucci, and Indonesia pages) are labeled as such on their respective pages, rather than presented as independently re-verified.

Every calculator result on this site is labeled as an estimate, not a guarantee. Finger size varies with time of day, temperature, and band width, and no at-home method — including ours — replaces an in-person measurement with a jeweler's ring sizer. Before buying anything that's expensive or difficult to resize (engagement rings, eternity bands, heavily set or engraved pieces especially), always confirm your size against the specific retailer's own chart or get measured in person.

There are no accounts and no server-side database — any size you save with the site's "saved sizes" feature stays only in your own browser. We use Google Analytics to understand aggregate site traffic; see the Privacy Policy for details.

Spotted a conversion figure that looks wrong, or have a brand/country chart to suggest? Email hello@ringsizeconvert.com — see the Contact page for more detail on what we can and can't help with.