Ring sizes by country
Ring sizes come in 7 systems on this site. The US and the UK use numbers and letters, most of Europe uses the inside circumference in millimetres, and Japan, Hong Kong, China and India use their own numbers. Each page gives the definition, where it is used and a full table.
Which system to read
A ring size is a way of writing one measurement: how far across, or how far round, the inside of the ring is. The systems differ in the unit and the starting point. The US and Canada count from a base diameter in steps of 0.8 mm. The UK counts letters of 1.25 mm of circumference. ISO and most of Europe write the circumference in millimetres, and Switzerland, Italy, Spain and India subtract 40 from it.
Japan, Hong Kong and China have no official definition we could find, so their numbers come from jewellers’ charts, and each page says how closely our table follows them. When a shop prints its own chart, use the shop’s chart: it is the one the ring was made to.
The systems at a glance
| System | Where | Defined by |
|---|---|---|
| US and Canada | United States, Canada | A published formula |
| UK, Ireland and Australia | United Kingdom, Ireland, Australia, New Zealand | A published standard |
| Europe (ISO 8653) | France, Austria, Belgium, Denmark, Finland, Norway, Sweden | A published standard |
| Switzerland, Italy and Spain | Switzerland, Italy, Spain | A published formula |
| Japan | Japan | No definition: a relation that fits published charts |
| Hong Kong and China | Hong Kong SAR China, China | No definition: a relation that fits published charts |
| India | India | No definition: a relation that fits published charts |
Sizes by country
US and Canada in detail
US and Canadian ring sizes use numbers in quarter steps. Read a size alongside the table’s measurements, then check the shop’s chart before choosing a ring.
UK, Ireland and Australia in detail
UK, Ireland and Australia ring sizes use letters, with each step tied to finger circumference. Read a letter as a position on the scale, then compare it with the shop’s chart before buying.
Europe (ISO 8653) in detail
Europe (ISO 8653) is a circumference-based ring sizing system used in France, Austria, Belgium and the Nordic countries. Read each size as the ring’s inside circumference in millimetres, rounded to a whole millimetre.
Switzerland, Italy and Spain in detail
Switzerland, Italy and Spain use whole-number ring sizes tied to ISO circumference. Read the number as a local size, then use the table to compare it with other systems.
Japan in detail
Japan ring sizes use a numbered go scale. Read the table by matching a Japan size with its inside diameter or circumference, then compare those measurements with the other systems shown.
Hong Kong and China in detail
Hong Kong and China sizes are trade conventions shown on jewellers’ charts. Read the table as a shop-specific guide, then check the seller’s chart before choosing a ring.
India in detail
India ring sizes are a jewellers’ numbering convention used in India. Read each number alongside the table’s measurements, since shops can use different scales and a shared size number may not mean the same ring.