What is my ring size in every country?
You bought a ring abroad. Or a friend abroad wants to send one. Or you saw a perfect ring on Etsy and the seller asks for a UK letter while all you know is a US 7. Sizes do not match across countries: US uses numbers, UK uses letters, Japan uses its own scale, and Poland / Germany / France just put the inner diameter in millimeters on the band.
Pick the system you know (PL, US, UK, JP, or a measurement in mm) and the converter shows you the equivalent in every other system, plus the inner diameter and circumference so you can double-check with a ruler at home. Below the conversion you get the two safest ways to measure a ring size without a sizer, plus tips that jewelers actually tell you in the shop.
The math behind it is ISO 8653:2016 (international standard) plus regional charts for US, UK, JP, HK and CN. Same numbers your jeweler uses.
How to use it
- Pick what you know at the top: a size in PL / DE / FR, a US number, a UK letter, a JP number, or a mm measurement (diameter or circumference).
- In the input field pick or type the value. For mm modes the converter snaps to the closest standard size and shows you the rounding error if it is bigger than 0.3 mm.
- The conversions card shows the size in five regional systems at once: PL / DE / FR, US, UK, JP, HK / CN.
- The neighborhood table shows two sizes above and two below the matched row, useful when you are between sizes or unsure of the measurement.
- Use the measurement guide cards below the table to size yourself at home with a piece of paper or an existing ring.
- Flip the wide band switch if the ring you are buying has a band wider than 6 mm (eternity, signet rings). The advice says to go up ½ size.
When this is useful
Five typical situations where this converter saves a return label:
- Buying a ring from a US Etsy seller while you know your Polish size. You wear a 17 mm in Poland. The seller asks: "what is your US size?". The converter shows US 7. You order with confidence, no measuring tape required.
- Sending a gift to a friend in Japan. Your friend in Tokyo wears JP 13. You go to a jeweler in Berlin who only speaks in mm. The converter shows that JP 13 = 17.3 mm inner diameter, you pick the right band in 30 seconds.
- Resizing an old family ring before passing it on. You inherited a ring marked N½ (UK system) and want to know if it fits a finger you measured as 53 mm circumference. The converter says N½ = 53.1 mm circumference: pretty much exact, no resize needed.
- Buying a wedding band online with confidence. The site lets you pick US 6, 7, 8, but you only have an old ring stamped 16 mm inside. The converter shows 16 mm = US 5.5. You pick US 6 (next half-size up) and skip the $30 return shipping.
- Translating between a UK jeweler and a US bride. The UK jeweler measured the bride at O½. The bride wants to surprise her with a stack from a US shop. The converter shows O½ = US 7.5: the surprise lands.