International Ring Size Hub
Know your size in one country's scale? Convert it to every supported system at once — US, UK, EU, German, Turkish, Japanese, and four Indian jeweler conventions — anchored to the shared millimeter measurement.
One size in, every system out
Tap your country, enter the size you know, and get the full international row.
Convert one size to every system
Pick your country (or system), enter the size you know, and see all equivalents plus the millimeter anchor.
How each system works
What the numbers mean, and how far to trust them — the same confidence levels used across this site.
US / Canada
VerifiedUS, Canada, Mexico
A numeric scale where each whole-size step adds a fixed amount of inner diameter (about 0.81 mm). Half sizes split the steps evenly.
Verified against the historical US Bureau of Standards relationship.
UK / Australia
VerifiedUK, Ireland, Australia, New Zealand, South Africa
A letter scale where each full letter adds a fixed amount of inner circumference (about 1.25 mm). Half-letters split the steps; the historical Q¼ irregularity is preserved as sourced.
Verified against the British Standards letter-step relationship.
EU
VerifiedEU, France, and most of continental Europe
Defined by ISO 8653:2016 as the inner circumference in millimeters, rounded to the nearest half-millimeter — an EU 57 is a ~57 mm circumference by definition.
Exact definitional relationship, not an approximation.
Germany / Netherlands
VerifiedGermany, Netherlands
The size number equals the inner diameter in millimeters, rounded to the nearest half-millimeter — a size 17 is a ~17 mm diameter by definition.
Exact definitional relationship, confirmed with retailer worked examples.
Turkey
VerifiedTurkey
The size number equals the inner circumference in millimeters minus 40 — a 52 mm circumference is about a Turkish size 12.
Corroborated at multiple rows by two Turkish jewelers.
Japan
Moderate confidenceJapan, China, South Korea, Hong Kong, Singapore
A regional numeric scale shared across East Asia per the corroborating sources. Values agree closely at small and mid sizes and drift by a size or two at the top end.
Corroborated by two sources with growing drift at larger sizes — treat as a close estimate.
India (BlueStone)
VerifiedIndia — Bluestone convention
Bluestone sizes equal inner circumference in millimeters minus 40, confirmed against every row of their published table.
Strongest India corroboration: Jewelove publishes the identical formula.
India (Jewelove)
VerifiedIndia — Jewelove convention
Jewelove sizes equal inner circumference in millimeters minus 40 — the same relationship Bluestone publishes independently.
Identical to the independently published Bluestone formula.
India (VowJewels)
Retailer-specificIndia — VowJewels convention
VowJewels sizes follow twice the US size minus two, derived from their own US/India cross-reference table.
Single-source convention — only use it when buying from VowJewels.
India (The Vedic Crystals)
Retailer-specificIndia — The Vedic Crystals convention
The Vedic Crystals sizes follow twice the US size minus one, as stated in their own guide and confirmed against their table.
Single-source convention — only use it when buying from that retailer.
Millimeters are the shared language
Why one converter can honestly cover every direction.
Every scale on this page is anchored to the same physical ring: its inner diameter and inner circumference in millimeters. Converting between systems is therefore a lookup through millimeters, not arithmetic between the scales — which is also why letter scales, diameter scales, and circumference scales can never line up with a simple formula. When a retailer quotes a size, ask for (or measure) the millimeter anchor and every other equivalent follows from it.
Dedicated pair guides
For directions converted often enough to deserve their own page — each with its own explanation and reference table.
- US to UK ring size
- UK to US ring size
- US to EU ring size
- EU to US ring size
- India to US ring size
- US to India ring size
- Australia to US ring size
- US to Australia ring size
- Turkey to US ring size
- US to Turkey ring size
- Japan to US ring size
- US to Japan ring size
- Germany to US ring size
- US to Germany ring size
- EU to UK ring size
- UK to EU ring size
Why only these pairs? New pair pages are added only where search data shows distinct, sustained demand for that exact direction. Every other direction is fully served by the all-systems converter above — deliberately, so the site never mass-produces thin near-duplicate pages.
Frequently asked questions
Why do ring sizes differ between countries at all?
Each scale grew out of its own jewelry trade: the US counts diameter steps, the UK counts circumference in letters, the EU writes the circumference in millimeters outright, and Germany writes the diameter. They describe the same physical ring in different units, which is why converting through the shared millimeter measurement — exactly what the converter above does — is the reliable route.
Which system does my country actually use?
Use the country chips above as a starting point: the US, Canada, and Mexico share the numeric scale; the UK, Ireland, Australia, New Zealand, and South Africa share the letter scale; most of continental Europe uses EU circumference numbers; Germany and the Netherlands use diameter numbers; Turkey subtracts 40 from the circumference; Japan shares its scale across East Asia. Retailers can still differ, so confirm against the shop you are buying from.
Why does India get four options instead of one?
India has no single universal ring-size standard — the generic India column in sizing tables cannot be verified. What can be verified are individual jewelers’ conventions: Bluestone and Jewelove independently publish the same circumference-minus-40 formula, while VowJewels and The Vedic Crystals each publish their own US-derived formulas. Pick the convention of the retailer you are buying from.
How exact are Japanese size conversions?
Close but not exact. Two independent sources corroborate the Japan scale and agree closely at small and mid sizes, with growing drift of a size or two at the top end. Treat Japanese conversions — and the shared East Asia scale covering China and South Korea — as a strong estimate, and confirm with the retailer for high-value pieces.
When should I use a dedicated pair page instead of this hub?
Use a pair page when you convert the same direction repeatedly — for example, shopping US stores from the UK every week — since it keeps the explanation and reference table for exactly that pair on one screen. This hub stays the better choice for one-off conversions in any direction, because it shows every system equivalent at once.
Will you add a conversion page for every possible country pair?
No. Dedicated pair pages are only added where search data shows distinct, sustained demand for that exact pair; everything else is served by this hub’s all-systems converter, which covers every supported direction without creating thin near-duplicate pages.