US to UK ring size conversion
A US size 7 is approximately a UK size N, a US 8 is a UK P, and a US 6 is a UK L. UK letters are approximations rather than exact units, so every conversion below is backed by the ring's millimetre measurements.
Why UK letters are only approximate
US sizes are defined by measurement: each full size adds about 0.81 mm of inside diameter. UK sizes use letters, and while the letters follow the same measurements, the steps between letters are not perfectly uniform and jewellers round them slightly differently. A ring sold as UK N by one maker can measure a hair over or under 17.3 mm. That is why this page — and jewellers themselves — treat the inside diameter and circumference in millimetres as the ground truth, and the letter as a label for it.
| US size | UK size (approx.) | Diameter (mm) | Circumference (mm) | EU size |
|---|---|---|---|---|
| 3 | F | 14.1 | 44.2 | 44 |
| 4 | H | 14.9 | 46.8 | 47 |
| 5 | J | 15.7 | 49.3 | 49 |
| 6 | L | 16.5 | 51.9 | 52 |
| 7 | N | 17.3 | 54.4 | 54 |
| 8 | P | 18.1 | 57.0 | 57 |
| 9 | R | 19.0 | 59.5 | 60 |
| 10 | T | 19.8 | 62.1 | 62 |
| 11 | V | 20.6 | 64.6 | 65 |
| 12 | X | 21.4 | 67.2 | 67 |
| 13 | Z | 22.2 | 69.7 | 70 |
Converting the other way
Going from a UK letter to a US size, find the letter in the table and read across — UK P is a US 8, UK R is a US 9. If your UK size falls between letters (some jewellers sell half letters such as N½), you are between the neighbouring US sizes too: N½ sits between US 7 and US 7.5. The converter on the homepage accepts UK letters directly, and the full chart includes every half size.
Frequently asked questions
What UK size is a US 7?
Approximately UK N — an inside diameter of 17.3 mm and a circumference of 54.4 mm (EU 54).
What US size is a UK L?
UK L corresponds to a US 6, measuring 16.5 mm in diameter and 51.9 mm in circumference.
Are Australian ring sizes the same as UK?
Yes — Australia and New Zealand use the same letter system as the UK, with the same approximate relationship to millimetre measurements.
Why did two shops give me different UK letters?
Because the letter boundaries are a convention, not a formula. A ring measuring 17.5 mm, for example, sits between N and O. If two jewellers disagree, trust the measurement in millimetres and try both sizes on.