Ring size chart

Every size, every system

US sizes are sold in quarters, so the chart is built in quarters. India, Italy, Spain, Switzerland and Brazil share one scale — inner circumference in millimetres minus 40 — which is why those columns agree. France is not on it: a French taille is the ISO number, so read France from the EU / ISO / FR column.

UK sizes run as long stretches of half letters. That is correct, not a bug: a US quarter step is 0.64 mm of circumference and a UK half letter is 0.625 mm, so the two scales drift against each other and never line up. Looking up a letter rather than a US size? The UK & Australian ring size chart lists every letter in order, half letters included. Why charts disagree

US 6¼ is the one row to read by circumference. Its exact size sits a hair over a boundary, so its diameter rounded to 16.71 mm, typed into the sizer, reads EU 52 and India 12 rather than EU 53 and India 13. Both are right for the figure typed; give a jeweller the circumference, 52.51 mm, which reads back exactly.

Women’s ring size chart

The range jewellers actually stock for women, US 3 to 9. The commonest is US 6. There is no census of finger sizes — these figures describe what sells, so treat them as a sanity check, not a verdict. What the averages actually mean.

Men’s ring size chart

US 8 to 14, with US 9 the commonest. The same caveat applies: this is what jewellers sell, not a measurement of the population.

Millimetres, centimetres and inches

These are the same measurement written three ways, so no conversion table is needed — divide millimetres by 10 for centimetres, or by 25.4 for inches. What matters far more is which measurement you have.

Inner diameter

Straight across the inside of the ring, edge to edge. This is the number every size system is built from, and the one to give a jeweller. US 6 is 16.51 mm.

Inner circumference

All the way round the inside — what a paper strip round your finger measures. It is exactly π × the diameter, which is why EU/ISO sizes are this number. US 6 is 51.87 mm.

Mixing the two up is the commonest sizing mistake there is, and it puts you out by roughly three times — a 16 mm circumference is a child’s ring; a 16 mm diameter is about US 5½.

Have a measurement, not a size?

The chart above runs in US quarter sizes, so its millimetres come out as 17.32 and 17.53 — figures no ruler gives you. These tables start from the round number you actually read and give the nearest size in every system. Use the one that matches how you measured; the difference between diameter and circumference is the one thing to get right.

Across a ring: inner diameter in millimetres

Straight across the inside of a ring that already fits, edge to edge, read to the nearest half millimetre.

Round the finger: inner circumference in millimetres

The flat length of a paper strip that went round the finger. This is also how Europe sizes rings — under ISO 8653 the size is this number — so the row for 54 mm is the row for an EU or French 54.

Round the finger, in inches

For a soft tape measure, marked in eighths or in tenths of an inch — both are listed. An eighth of an inch round the finger is 3.17 mm and a tenth is 2.54 mm, while a whole US size is 2.55 mm of circumference, so an inch tape cannot see quarter sizes. If it has millimetres on the other side, use those and the table above.

Each row is exact for the figure in its first column; your reading has an error of its own. Misjudge a ring’s inside diameter by a quarter of a millimetre and the answer moves by more than a US quarter size, which is only 0.2032 mm. Measure twice. If you fall between two rows, type the exact figure into the ring sizer. The tables stop at US 3 and US 15½, the range the chart above covers.

How each country’s sizes work

Every system is a different label for the same inside measurement. Here is what each label means, how to convert it both ways, and where charts for it disagree.

US and Canada

No standards body defines US sizes; every maker uses the same trade rule. Size 0 is 0.458 in (11.63 mm) across the inside and each whole size adds 0.032 in (0.8128 mm), so a quarter size — the smallest step sold — is 0.2032 mm. Canada uses the same scale.

A US 7 is 11.6332 + 7 × 0.8128 = 17.32 mm across and 54.42 mm round: UK N½, EU 54, Japan 14. Going back, subtract 11.6332 from the diameter and divide by 0.8128: 18 mm gives 7.83, so US 7¾.

UK, Ireland, Australia and New Zealand

Letters, measured round the inside: A is 37.5 mm and every letter adds 1.25 mm, with half letters between. After Z the scale carries on as Z+1, Z+2 and so on.

To turn a letter into millimetres, count its steps from A and multiply by 1.25. T is 19 steps, so 37.5 + 19 × 1.25 = 61.25 mm round and 19.50 mm across: US 9¾, EU 61, Japan 20. M, the letter asked about most, is 52.50 mm round, which is US 6¼.

Going from a US size to a letter often lands on a half letter, because a US quarter and a UK half letter are almost, but not quite, the same step. If your jeweller stocks whole letters only, go up — the worked US 6 example shows why. Every letter from A to Z+6 in order, with its millimetres, is on the UK & Australian ring size chart.

Europe (ISO 8653) and France

The plainest system there is: the size is the inside circumference in millimetres, so a 54 is 54 mm round. ISO 8653 defines sizes 41 to 76, and France uses the same numbers for its taille.

Because a size is a whole millimetre, each one covers half a millimetre either side — which is why the chart above prints EU 54 against both US 6¾ and US 7. A ring made to exactly 54 mm is US 6¾. To convert, find your size in the circumference table: the row for 54 mm is the row for EU 54.

Japan

Japanese shops number rings 1 to 35 (号, gō). Size 1 is 13 mm across and each size adds a third of a millimetre, so 15 mm is a 7, 16 mm a 10 and 19 mm a 19. It is a trade convention: Japan’s industrial standard, JIS S 4700, numbers rings by circumference, like ISO.

One Japanese step is 0.33 mm of diameter against 0.20 mm for a US quarter, so the US column below moves unevenly — a quarter here, a half there. That is the two scales, not a gap. Sizes 4 to 34 fall inside the chart’s US 3–15½ range:

India

India has no official ring size standard. Most Indian jewellers number rings by the inside circumference in millimetres minus 40, so an Indian 14 is 54 mm round — US 6¾, EU 54 — and that is what this site shows. Tanishq’s chart runs about one size smaller. To convert, add 40 and read the circumference table; to be safe, give an Indian jeweller the diameter in millimetres, the one figure no chart can disagree about. How we checked.

Italy, Spain, Switzerland and Brazil

The same arithmetic as India — circumference minus 40 — and in Brazil a standard stands behind it: ABNT NBR 16058, aligned to ISO 8653. A Brazilian aro 19 is 59 mm round and 18.78 mm across: US 8¾, EU 59. An Italian 14 is an Indian 14 and a French 54.

Spain is the one to check before you buy. Some Spanish shops use the minus-40talla shown here; others label a talla as the plain ISO circumference, so their talla 54 is 54 mm round. Ask which scale a Spanish chart uses, or give the shop the millimetres.

Where these numbers come from

Two systems have no standard behind them, and we say so rather than presenting a number as settled. India has no BIS specification; Tanishq’s own chart runs about a size smaller than the convention four other Indian jewellers publish. UK letter charts vary by up to half a size depending on which half letters a given scale includes.

The full working — including where four ranking sites give three different UK answers for the same ring — is on the ring sizer page.

Ring size chart questions

Taken word for word from Google’s “People also ask”. Nothing here is invented to pad the page.

Every answer below is written straight into the page — open or closed, it is already there, nothing loads only after a click. We checked seven of the top-ranking ring-sizer pages the way a search engine actually reads them rather than the way a person browsing does: fetch and read, nothing clicked. Six of the seven returned under 130 words apiece, and two listed their FAQ questions with no answers attached at all — because those only appear once a visitor expands them.