Reference
Ring size chart
This is the cross-country conversion table: one row per half US size, with the UK letter, the EU/ISO number, the Indian and the Japanese size that share it. Use it when you know a size in one system and need it in another. If you only need US sizes and the arithmetic behind them, theUS ring size chartgoes deeper on that one system. Do not know your diameter yet? Measure it with theon-screen sizer, which is accurate to about±0.15 mm once calibrated.
Instant converter
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- US / CA
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- UK / AU
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- EU / ISO
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- India
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- Japan
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- Circumference
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No calibration needed — this is pure conversion. Measure now
| Ø mm | Circ. mm | US / CA | UK / AU | EU / ISO | India | Japan |
|---|---|---|---|---|---|---|
| 13.3 | 41.6 | 2 | D | 42 | 2 | #2 |
| 13.7 | 42.9 | 2½ | E | 43 | 3 | #3 |
| 14.1 | 44.2 | 3 | F | 44 | 4 | #4 |
| 14.5 | 45.5 | 3½ | G | 45 | 5 | #5 |
| 14.9 | 46.8 | 4 | H | 47 | 7 | #6 |
| 15.3 | 48.0 | 4½ | I | 48 | 8 | #8 |
| 15.7 | 49.3 | 5 | J | 49 | 9 | #9 |
| 16.1 | 50.6 | 5½ | K | 51 | 11 | #10 |
| 16.5 | 51.9 | 6 | L | 52 | 12 | #11 |
| 16.9 | 53.1 | 6½ | M | 53 | 13 | #13 |
| 17.3 | 54.4 | 7 | N | 54 | 14 | #14 |
| 17.7 | 55.7 | 7½ | O | 56 | 15 | #15 |
| 18.1 | 57.0 | 8 | P | 57 | 17 | #16 |
| 18.5 | 58.2 | 8½ | Q | 58 | 18 | #17 |
| 18.9 | 59.5 | 9 | R | 60 | 19 | #18 |
| 19.4 | 60.8 | 9½ | S | 61 | 21 | #19 |
| 19.8 | 62.1 | 10 | T | 62 | 22 | #21 |
| 20.2 | 63.3 | 10½ | U | 63 | 23 | #22 |
| 20.6 | 64.6 | 11 | V | 65 | 25 | #23 |
| 21.0 | 65.9 | 11½ | W | 66 | 26 | #24 |
| 21.4 | 67.2 | 12 | X | 67 | 27 | #25 |
| 21.8 | 68.5 | 12½ | Y | 68 | 28 | #27 |
| 22.2 | 69.7 | 13 | Z | 70 | 30 | #28 |
Diameter or circumference? Diameter is the straight line across the inside of the ring; circumference is the distance around it. They are related bycircumference = diameter × π, so either one gives the other.
Between two rows? Take the larger. A ring a little loose can be beaded or resized; one that will not pass your knuckle cannot be worn at all.
Working in one system only? TheUS ring size chartlists every US size from 3 to 13.5 in millimetres with the formula the scale is built on, themen's ring size chartcovers US 7 to 15 with the band-width allowance wide rings need, andaverage ring size for womenis the place to start when you are sizing a ring for somebody else.
The five systems
Why the same finger has five different numbers
- United States & Canada
- A number from about 2 to 15 in quarter-size steps. Each whole size adds 2.55 mm of inside circumference, or about 0.81 mm of diameter.
- United Kingdom, Australia & New Zealand
- Letters A to Z, then Z+1 upward, in half-letter steps. One letter is roughly half a US size.
- Europe (EU / ISO 8653)
- The size is simply the inside circumference in whole millimetres, which is why EU numbers run from the forties to the seventies.
- India
- A number from 1 to about 30. Indian jewellers often quote the UK letter as well, since the two systems are used side by side.
- Japan
- A number from #1 to about #30, written with a hash. Half sizes are rare, so round up when you fall between two.
By country
Fourteen countries, six scales, one millimetre
No country has a sizing system of its own — each adopts one of a handful of scales, and several share each one. Pick where you are ordering from and this gives the local number for the same finger. Where local practice is genuinely mixed, it says so instead of guessing.
Do not know it? Measure a ring on your calibrated screen — it is the only number here that is not a conversion of another number.
Indian numeric
14
A number from 1 to about 30. Indian jewellers frequently print the UK letter beside it, because both are in daily use.
India. Indian jewellers quote a numeric scale of their own, roughly 1 to 30. Tanishq, Malabar Gold, Kalyan and GIVA all use it, and many print the UK letter beside it. Online-first brands often list US sizes as well, so check which scale a listing means before ordering. Full India ring size chart.
United States. The US numeric scale, sold mostly in half sizes. Quarter sizes exist and a jeweller can cut them, but they are rarely stocked. Full USA ring size chart.
United Kingdom. Letters, in half-letter steps. British hallmarked rings are usually stamped with the letter, so an inherited ring often tells you its own size if you look inside the band. Full UK ring size chart.
Europe. France, Germany, the Netherlands and Scandinavia quote the ISO 8653 number, which is the inside circumference in millimetres. Italy, Spain and Switzerland quote the same measurement minus 40, so a 54 becomes a 14. Full Europe ring size chart.
Japan. The Japanese numeric scale runs #1 to about #27 for the sizes people actually order. Mikimoto, Tasaki and 4°C all use it. Japanese sizes are usually whole numbers only. Full Japan ring size chart.
China. Mainland Chinese listings usually give 圈号 — the inside circumference in millimetres, the same number as EU/ISO. Hong Kong uses a separate numbered scale, and marketplace listings mix both with US sizes. Order by inside diameter in millimetres when a listing does not say which scale it means.
Australia. Australia and New Zealand use the UK letter scale unchanged, so a UK N is an Australian N.
Canada. Identical to the United States. A US 7 is a Canadian 7, with no conversion in between.
Singapore. Singapore retail is mixed: international brands quote US numbers, goldsmiths in the Chinese tradition quote Hong Kong numbers, and British-founded chains quote letters. Ask for the inside diameter in millimetres and you sidestep the whole problem.
Malaysia. As in Singapore, US numbers dominate modern retail while traditional goldsmiths use Hong Kong numbers. Confirm the scale, or the diameter, before you order.
United Arab Emirates. Gulf retail quotes US sizes most often. British-founded chains use letters, and the many Indian gold houses in Dubai use the Indian scale, so the same finger can be quoted three ways along one street.
South Africa. South Africa follows the UK letter scale. Online stores that ship from the United States will quote numbers instead.
Brazil. Brazilian sizes are the inside circumference in millimetres minus 40 — the same arithmetic Switzerland uses. A 54 mm circumference is a Brazilian 14.
Mexico. Mexican jewellers use a local numeric scale that is not the US one, and the published conversions for it disagree with each other. We will not print a number we cannot stand behind, so order by inside diameter in millimetres, or ask the retailer for the diameter of the size they are offering. Large chains and online stores generally quote US sizes.
Single conversions
If you only need one conversion
- MM to ring sizeA diameter in millimetres into every scale, plus how to tell a diameter from a circumference.
- US to UK ring sizeNumbers to letters and back, and why the two scales never line up on whole steps.
- Ring size in cmThe centimetre reading a paper strip gives you, converted — and why it tends to read small.
- Kids ring size chartUS 0 to 5, typical sizes by age, and why a child’s knuckle changes the advice.
- Ring sizes by brandTiffany, Pandora, Tanishq, Mikimoto and the rest — eleven houses, five scales.
- Oura ring sizeWhy a smart ring sizes differently, and what a chart cannot tell you about it.
Questions
Ring size conversion, answered
How do I convert my ring size between US, UK and EU?
Find the row for a size you already know and read across. The two millimetre columns are the measurements everything else derives from: the EU/ISO number is the inside circumference in millimetres, so a 54 mm circumference is EU size 54. US, UK, Indian and Japanese numbers do not follow a formula from each other, which is why a table is needed rather than a conversion sum.
What ring size is 17 mm in diameter?
An inside diameter of 17.0 mm is about US 6½, UK N, EU 53 and Japan #13. Multiply the diameter by 3.1416 to get the inside circumference — 17.0 mm across is 53.4 mm around. Use the mm to ring size page if you are starting from a millimetre measurement.
Is a UK ring size the same as a US one?
No. UK and Australia use letters, the US and Canada use numbers, and the two scales are offset rather than parallel — UK “N” sits near US 6½. One UK letter is roughly half a US size. See US to UK ring size for the full letter-by-letter mapping.
What is the most common ring size?
For women the most common sizes cluster around US 6 to 7 (EU 52–55); for men, US 9 to 11 (EU 59–65). These are distributions, not defaults — the spread is wide enough that ordering on the average is a coin flip. Measure a ring that already fits instead.
Are ring sizes the same at every jeweller?
The ISO 8653 standard is, but practice is not quite. Some brands round differently or manufacture to their own tolerances, so a size from one maker can sit a quarter size away from another. For an expensive purchase, check the maker’s own chart as well as this one.
Why is there no Mexican ring size in the table?
Because the published Mexican conversions contradict each other. Rather than invent a number, this chart gives the inside diameter in millimetres for that market and says why — a wrong size printed with confidence is worse than an honest gap.
Know the size but not the diameter?
Measure an existing ring on your calibrated screen and get all five numbers at once.
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