Ring Size Chart & Converter
US, UK, EU, Japan & mm.
US, UK, EU, Japan & mm.
How to use Ring Size Chart & Converter
- Enter a ring size in US, UK, EU, or Japan, or a mm measurement
- See every system's equivalent calculated at once
- Scroll the full chart to check diameter and circumference values
About Ring Size Chart & Converter
Convert a ring size between US/Canada, UK/Australia, EU (ISO) and Japan in one step — or start from a physical measurement, a diameter or circumference in millimetres, and get every system's equivalent at once. Type a US number, a UK letter, an EU (ISO) size or a Japanese size and the tool fills in all the others, so you can turn a UK letter into a US number, an EU size into a UK letter, or match a size across any two regions.
Below the converter is a full ring size chart lining up every system side by side, which is handy when a store lists sizes in a standard you don't use. Because the EU column follows ISO 8653 (the size equals the ring's inner circumference in millimetres), it also matches the way brands like Pandora label their rings. If your measurement is in centimetres or inches rather than millimetres, convert it first — multiply centimetres by 10, or inches by 25.4 — then enter the result as the circumference and the tool finds the closest standard size.
Every conversion happens the moment you type, with the diameter and circumference shown so you can double-check against a ring you already own. It's completely free, needs no sign-up, and runs entirely in your browser — nothing you enter is uploaded anywhere.
It doubles as a full ring size chart: every system's size sits side by side, so you can read the whole chart at a glance or convert a single size.
Frequently asked questions
- What is a US 7 ring size in the UK and EU?
- A US 7 is about a UK N½ and an EU (ISO) 54, with an inside diameter of roughly 17.3 mm. Enter any size in the tool to see all the equivalents at once.
- How do I convert a ring size from millimetres?
- Choose 'Diameter (mm)' or 'Circumference (mm)' as your input and type the measurement — the tool finds the closest standard ring size and shows every system's equivalent. Measure the inside diameter of a ring that fits, or the length of a strip wrapped around your finger for the circumference.
- How do I convert inches to a ring size?
- Ring measurements given in inches are almost always the finger's circumference. Multiply the inches by 25.4 to get millimetres, pick 'Circumference (mm)' as your input, and enter that number — the tool then finds the closest standard size in every system.
- What ring size is 2.5 inches?
- 2.5 inches is a circumference of about 63.5 mm (2.5 × 25.4), which works out to roughly a US 10½, or EU 63. Enter 63.5 as the circumference to see the exact equivalents in every system.
- How do I convert cm to a ring size?
- A ring sizer that reads in centimetres is giving a circumference, so multiply the centimetres by 10 to get millimetres — 5.4 cm is 54 mm. Enter that as the circumference and the tool matches it to a standard size; 54 mm is an EU 54, about a US 7.
- What is a UK ring size letter in numbers?
- UK and Australian sizes use letters while US, EU and Japanese sizes use numbers. Enter a UK letter and the tool shows the matching US number, EU (ISO) size and diameter — a UK N½, for example, lines up with a US 7 and an EU 54.
- What ring size are Pandora rings?
- Pandora labels its rings with the European (ISO 8653) number, which is the ring's inner circumference in millimetres, so a Pandora 54 is an EU 54. Enter that number in the EU field, or match by circumference, to see the US, UK and Japanese equivalents.
- How do I convert an EU ring size to UK?
- Type your EU (ISO) size and read the UK column — an EU 54 is about a UK N½, which is also a US 7. Because EU sizes follow the inner circumference in millimetres, you can also match by circumference if a chart numbers things differently.
- Does this include Japanese ring sizes?
- Yes — Japan is one of the four systems the tool converts between, alongside US/Canada, UK/Australia and EU. Enter any US, UK or EU size (or a millimetre measurement) and the matching Japanese size appears in its own column, with the full chart below for cross-checking.
- Which EU ring size system does this use?
- The EU column uses ISO 8653, where the size equals the ring's inner circumference in millimetres. Some French and continental charts number rings differently, so when in doubt match by diameter or circumference.
- How can I measure my ring size at home?
- Measure the inside diameter of a ring that already fits, in millimetres, and enter it as the diameter — or wrap a strip of paper around your finger, mark it, and measure the length as the circumference.
- What if I'm between two sizes?
- Size up rather than down, and measure at the end of the day when fingers are at their largest, since a ring that's slightly loose is far easier to wear than one that's too tight.