1. Cut a strip
Paper or thin card, about five millimetres wide and longer than you think — ten centimetres is plenty. Not string: string stretches and gives a size that is too small.
Guides
Ring size chart, and how to measure at home
Nearly every surprise proposal involves a guess at the size, and nearly every guess is close enough — because most solitaires can be resized afterwards. Here is the chart, the way to measure it properly, the ways to find it secretly, and what to do when you cannot.
Last updated 2026-09-20
The ring size chart
Four systems describe the same measurement. The US and Canada use numbers, the UK and Australia letters, most of Europe and Asia the inside circumference in millimetres, and a jeweller's ring stick reads the inside diameter. The millimetre columns are the physical truth; the letters and numbers are labels for them.
| US / Canada | UK / Australia | EU (circumference, mm) | Inside diameter (mm) |
|---|---|---|---|
| 4 | H | 46.8 | 14.9 |
| 4½ | I | 48.1 | 15.3 |
| 5 | J | 49.3 | 15.7 |
| 5½ | K | 50.6 | 16.1 |
| 6 | L | 51.8 | 16.5 |
| 6½ | M | 53.1 | 16.9 |
| 7 | N | 54.4 | 17.3 |
| 7½ | O | 55.6 | 17.7 |
| 8 | P | 56.9 | 18.1 |
| 8½ | Q | 58.1 | 18.5 |
| 9 | R | 59.4 | 18.9 |
| 9½ | S | 60.9 | 19.4 |
| 10 | T | 62.2 | 19.8 |
| 10½ | U | 63.5 | 20.2 |
| 11 | V | 64.7 | 20.6 |
| 11½ | W | 66.0 | 21.0 |
| 12 | X | 67.2 | 21.4 |
How to measure at home — the paper-strip method
This is what a jeweller does at the counter when there is no ring to copy, and it works just as well at a kitchen table. The clip shows it in eight seconds.
2. Wrap it at the base of the finger
Snug, not tight. It should sit the way a ring sits — close to the skin without indenting it. Wrap it where the ring will actually live, at the base, not further up.
3. Mark the overlap
A pen mark where the strip crosses itself. Do it three times and take the middle result; the first attempt is nearly always pulled tighter than the others.
4. Measure it flat, in millimetres
Lay the strip against a ruler and read the distance from the end to the mark. That number is the inside circumference — the EU column above. Find the nearest row and you have the size in every system.
5. Check the knuckle
A ring has to get past the knuckle to reach the base. If the knuckle is clearly bigger than the base of the finger, measure it too, and size between the two — closer to the knuckle. A ring that cannot get on is not a ring.
Finding her size without asking
Borrow a ring she already wears on that finger
The most reliable method there is. A ring from the ring finger of the correct hand, pressed into a bar of soap or traced around its inside edge on paper, gives us the size to within a quarter. Better still, bring it to a jeweller for an hour. A ring from a different finger is a different size.
Ask someone who knows
A sister, a mother, a close friend — someone who has borrowed her rings or bought her one. Surprisingly often, somebody already knows.
Measure while she sleeps
The paper-strip method above, gently. It works and it is the least accurate of these: fingers are smaller at night, and a nervous measurer pulls tight. Round up, not down.
Guess, and size later
The most common method in practice, and a fine one, because a solitaire can be resized. Most women take between a US 5½ and a 7½; a US 6½ — UK M, about 53 mm — is the single most common. Choose that, and plan on a resize.
Band width changes the size
A size measured with a thin strip is the size for a thin ring. A wide band — four millimetres and up — covers more of the finger and has nowhere to sit in the natural dip at the base, so it fits tighter than a slim band of the same nominal size. For anything over four millimetres, go up a quarter to a half size. A comfort-fit band, rounded on the inside, sits looser than a flat one of the same size and can go the other way.
This is why we ask what the ring is before sizing it, and why a solitaire and the wide band bought to sit beside it are not always the same number.
Fingers change — measure accordingly
A finger is smallest first thing in the morning and in cold weather, largest in the evening, in heat, after salt or alcohol, and during pregnancy. Measure in the afternoon, at normal room temperature, on an ordinary day. A ring should slide over the knuckle with a little resistance and turn on the finger with a little effort; if it spins freely it is too big, and if it needs soap to come off it is too small.
What can be resized, and what cannot
A plain band or a solitaire with a plain shank resizes easily, up or down, by a size or two — the band is cut, metal added or removed, and the join polished away. This is routine, and we do it once at no charge on any ring we have made.
A half eternity resizes, because the underside is plain. A full eternity does not: there is no plain metal to cut. A pavé band with stones most of the way round is somewhere between. If you are guessing the size, do not guess on a full eternity.
Questions people ask
What is the most common ring size?
For women, a US 6½ — UK M, about 53 mm around. For men, a US 10 — UK T, about 62 mm. If you have to guess with nothing to go on, guess those and plan to resize.
How do I convert my ring size from UK to US?
Use the chart above: each UK letter is roughly one US half-size, so a UK L is a US 6 and a UK N a US 7. If you have the size in millimetres, use that instead — it is the only column every chart agrees on.
Is it better to guess too big or too small?
Slightly too big. Making a ring smaller is easier than making it larger, and a ring that will not go on is a worse proposal than one that turns a little.
Do you resize rings you have made?
Yes, once, at no charge, on any ring from this bench. Send it back with the measurement and it is done and returned insured.
Not sure of the size?
Tell us what you know — a borrowed ring, a paper-strip number, a guess, nothing at all — and we will make it to the best estimate and resize it once for free after the surprise. That is how most of them are done.