Country chart — United Kingdom

UK ring size chart

The UK system: letters from A (smallest) to Z (largest), with half letters between them. The UK, Ireland, Australia and New Zealand all use this letter system — but not with identical millimetre values, which is why UK is labelled approximate on this site.

How the UK system works

Letters, not numbers

A is the smallest, Z the largest. Beyond Z, jewellers extend with Z+1, Z+2 and so on rather than continuing the alphabet.

Each whole letter is about 1.27 mm

A whole letter step adds roughly 1.27 mm of inner circumference (about 0.4 mm of diameter). A half letter is half that step — about 0.63 mm of circumference.

Half letters are standard in the UK

Most UK jewellers stock half letters (L½, M½, and so on). The converter on this site accepts them as interpolated midpoints between whole letters.

UK native ladder — whole letters

UK native ring size ladder, whole letters E to Z, with inner diameter and circumference.
UK letter	Inner diameter	Inner circumference
E	13.7 mm	43.0 mm
F	14.1 mm	44.3 mm
G	14.5 mm	45.5 mm
H	14.9 mm	46.8 mm
I	15.2 mm	47.8 mm
J	15.6 mm	49.0 mm
K	16.0 mm	50.3 mm
L	16.4 mm	51.5 mm
M	16.8 mm	52.8 mm
N	17.2 mm	54.0 mm
O	17.6 mm	55.3 mm
P	18.0 mm	56.5 mm
Q	18.4 mm	57.8 mm
R	18.8 mm	59.0 mm
S	19.2 mm	60.3 mm
T	19.5 mm	61.2 mm
U	19.9 mm	62.5 mm
V	20.3 mm	63.8 mm
W	20.7 mm	65.1 mm
X	21.1 mm	66.4 mm
Y	21.5 mm	67.7 mm
Z	21.9 mm	68.8 mm

Letters A–D are smaller than E and are omitted from most adult charts; they follow the same ~1.27 mm step downwards. Values above are the Queensmith published ladder; see the disagreement note below.

Warning: Why UK charts disagree: the same ring is L on the simplified US-aligned chart used in the international table, L½ on half-letter charts, and between L (51.5 mm) and M (52.8 mm) on this native ladder — all for a 51.9 mm circumference. The differences are under 0.7 mm, less than a half US size, but they are real, and they are why this site never presents a UK letter as exact. If you are ordering from a UK jeweller, confirm against that jeweller's own chart, or give them the millimetre circumference.

Conversion examples

UK L → about US 6

Native L is 16.4 mm / 51.5 mm; the unified chart's US 6 is 16.51 mm / 51.9 mm. The 0.1–0.4 mm gap is the UK disagreement in miniature.

UK N → about US 7

Native N is 17.2 mm / 54.0 mm; US 7 is 17.32 mm / 54.4 mm. Half-letter charts call the US 7 ring N½ instead.

UK T → about US 10

Native T is 19.5 mm / 61.2 mm; US 10 is 19.76 mm / 62.1 mm. Again, close — not identical.

Original references

British Standard BS 8721 is cited by UK retailers as the letter-scale standard, but its full text is not freely available, so this site does not quote it as a verified source — it uses the retailer-published ladders above and labels the result approximate. That distinction is deliberate.

Related guides

International ring size chart
All systems on one table.
US ring size chart
The number system UK letters convert to.
Ring size converter
Convert a UK letter (including halves) to any other system.