Converter · US ↔ UK
US to UK ring size
A US 7 is a UK N½. A US 6 is a UK L½. The two scales are built on different steps — 0.81 mm of diameter per US size against about 0.4 mm per UK letter — so they never line up on whole steps, and every conversion between them involves a small rounding. The table below shows exactly where.
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The table
US sizes to UK letters
Read left to right for US to UK, right to left for UK to US. The millimetre columns are the physical fact both scales are labelling.
| US / CA | UK / AU | Ø mm | Circ. mm | EU / ISO |
|---|---|---|---|---|
| 3 | F | 14.1 | 44.2 | 44 |
| 3½ | G | 14.5 | 45.5 | 45 |
| 4 | H | 14.9 | 46.8 | 47 |
| 4½ | I | 15.3 | 48.0 | 48 |
| 5 | J | 15.7 | 49.3 | 49 |
| 5½ | K | 16.1 | 50.6 | 51 |
| 6 | L | 16.5 | 51.9 | 52 |
| 6½ | M | 16.9 | 53.1 | 53 |
| 7 | N | 17.3 | 54.4 | 54 |
| 7½ | O | 17.7 | 55.7 | 56 |
| 8 | P | 18.1 | 57.0 | 57 |
| 8½ | Q | 18.5 | 58.2 | 58 |
| 9 | R | 18.9 | 59.5 | 60 |
| 9½ | S | 19.4 | 60.8 | 61 |
| 10 | T | 19.8 | 62.1 | 62 |
| 10½ | U | 20.2 | 63.3 | 63 |
| 11 | V | 20.6 | 64.6 | 65 |
| 11½ | W | 21.0 | 65.9 | 66 |
| 12 | X | 21.4 | 67.2 | 67 |
| 12½ | Y | 21.8 | 68.5 | 68 |
| 13 | Z | 22.2 | 69.7 | 70 |
Derived from ISO 8653. Where a US size falls between two letters the table gives the nearer one; if you are ordering and the half-letter is available, take it.
Why the two scales do not line up
The American scale is linear in circumference: each whole size adds 2.5535 mm around the inside, which is 0.81 mm across it. The British scale is alphabetic and steps about half as far — roughly 0.4 mm of diameter per letter, half that again for a half-letter.
Two different step sizes on the same underlying millimetre mean the two scales drift in and out of alignment as you climb. A US 6 lands almost exactly on a UK L½, while a US 8 lands between P and P½. So a conversion is always a rounding, and a conversion of a conversion compounds it.
The practical consequence: if you have a US size that somebody else already converted from a UK letter, do not convert it back. Go to the millimetre instead. One hop rounds a little, two hops can move you a full size.
Common conversions
The sizes people ask for most
- US 6 → UK L½
- 16.5 mm inside diameter, 51.9 mm around. The centre of the women’s range in both markets.
- US 7 → UK N½
- 17.3 mm inside diameter, 54.4 mm around — an EU 54, and the size most often quoted as "average".
- US 10 → UK T½
- 19.8 mm inside diameter, 62.1 mm around. The middle of the men’s range on both scales.
Beyond the two
The same finger in every other market
Australia, New Zealand and South Africa read the UK letter; Canada reads the US number. Pick a market for the rest.
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.
Questions
US and UK sizes, answered
What is a US 7 in UK size?
A UK N½, an inside diameter of 17.3 mm. Some charts round it to N — the difference is about 0.2 mm.
What is UK size L in US?
About a US 5¾. UK L½ is a US 6, and UK M is a US 6¼.
Is a UK letter half a US size?
Roughly, yes — one letter is about half a US size, so two letters make about one US size. It is an approximation rather than a definition, which is why the scales drift.
Which is more precise?
The UK scale, marginally, because its steps are smaller. In practice both are finer than most people can measure at home without a calibrated tool.
Do Australian rings use UK or US sizes?
UK letters, unchanged. Australia and New Zealand read the same alphabet as Britain.
Skip the conversion entirely
Measure the ring itself and get the US number, the UK letter and every other scale from one reading, with no rounding in between.