

A ring is on its way to you – or you’re about to choose one. Either way, you’re in the right place with our ultimate guide to ring sizes.
Getting your ring size right is one of those small details that makes a huge difference. Too tight and it won’t go on; too loose, and it might not stay on.
Whether you’re secretly planning a proposal (40% of UK engagements happen between November and February, and Christmas Day is the most popular day of all, according to our UK Wedding Report), shopping together, or just doing your research, we’ve got you covered.
Use our free Bridebook Ring Sizer tool below to find your size in seconds, then keep reading for everything you need to know about measuring at home, converting between international sizes, and nailing the fit.
Good news: you don’t need a jeweller to figure out your ring size. These methods are reliable, quick, and require nothing you don’t already have at home.
One golden rule before you start: always measure in the evening. Fingers are at their largest later in the day, when they’re slightly swollen from warmth and activity.
A morning measurement can be up to half a size smaller – and a ring that fits perfectly in the evening will never feel too tight. If you land between two sizes, always go up.

You’ll need: a thin strip of paper, a pen, and a ruler.

You’ll need: a ring that fits the correct finger, and a ruler.
Planning a surprise proposal? This is your method. Borrow a ring your partner wears on their ring finger – even for two minutes – and you’ll have everything you need. According to Bridebook data, the average UK couple spends £2,247 on an engagement ring, so it’s worth getting this right.

Again, another secret ring sizing method. You need a ring and a bar of soap.

A bit less messy than the soap method, the candle method is great if you’re trying to secretly find out your partner’s ring size, and you can’t steal one of their rings to take to a jeweller.
You’ll need a tapered candle and a ring.

Whether you’re buying from a UK jeweller or shopping internationally, this chart has you covered. You’ll see that the UK uses letters, the US uses numbers, and the EU uses circumference in millimetres. All measurements follow British Jewellers’ Association (BJA) standards.
Note that sizing can vary slightly between individual jewellers, so if you’re ever in doubt, ask for a professional fitting before you commit.
UK Size | Diameter (mm) | Circumference (mm) | US Size | EU Size |
F | 14.1 | 44.2 | 3 | 44 |
G | 14.5 | 45.5 | 3.5 | 45.5 |
H | 14.9 | 46.8 | 4 | 47 |
I | 15.3 | 48.0 | 4.5 | 48 |
J | 15.7 | 49.3 | 5 | 49 |
K | 16.1 | 50.6 | 5.5 | 50.5 |
L | 16.5 | 51.9 | 6 | 52 |
M | 16.9 | 53.1 | 6.5 | 53 |
N | 17.3 | 54.4 | 7 | 54 |
O | 17.7 | 55.7 | 7.5 | 55.5 |
P | 18.1 | 57.0 | 8 | 57 |
Q | 18.5 | 58.3 | 8.5 | 58 |
R | 18.9 | 59.5 | 9 | 59.5 |
S | 19.4 | 60.8 | 9.5 | 61 |
T | 19.8 | 62.1 | 10 | 62 |
U | 20.2 | 63.4 | 10.5 | 63.5 |
V | 20.6 | 64.6 | 11 | 64.5 |
W | 21.0 | 66.0 | 11.5 | 66 |
X | 21.4 | 67.2 | 12 | 67 |
Y | 21.8 | 68.5 | 12.5 | 68.5 |
Z | 22.2 | 69.7 | 13 | 70 |
Z+1 | 22.6 | 71.0 | 13.5 | 71 |
Z+2 | 23.0 | 72.3 | 14 | 72 |

If you’re buying a ring as a surprise and measuring isn’t possible, these averages are a useful starting point.
The average ring size for women in the UK is L to N. For men it’s T to V. These are starting points, not guarantees (fingers vary enormously and there’s no such thing as a “standard” hand). Always check the jeweller’s resizing and returns policy before you buy.
Worth knowing: most rings can be resized in one or two sizes in either direction without any issue. The exception is eternity rings and full-pavé bands where stones run all the way around – these are extremely difficult to resize, so accurate measurement matters even more for those styles.
A few things that can affect your ring size that are genuinely worth knowing:

The average ring size for women in the UK is between L and N, with N being the most cited average.
If you’re buying a surprise engagement ring and can’t measure, N is a reasonable starting point, but always check the resizing policy.
The average ring size for men in the UK is between T and V. Men’s ring sizes vary more widely than women’s, so if you can get any measurement at all – even an approximate one using the existing ring method – it’s worth doing.
Yes. Ring size can change with age, weight fluctuation, pregnancy, temperature, and even the time of day.
If a ring you’ve worn for years suddenly feels tight or loose, it’s worth getting professionally measured again rather than assuming your size hasn’t changed.
Always size up. A ring that’s slightly loose is far easier to resize than one that won’t go past your knuckle. For wide bands specifically, go up at least half a size as wider bands fit tighter than narrow ones.
The easiest method is the existing ring method; borrow a ring your partner already wears on their ring finger (even briefly while they’re asleep or in the shower) and measure the inner diameter with a ruler.
Alternatively, trace the inside of the ring onto paper and bring that to the jeweller. If all else fails, buy the most likely size, choose a jeweller with a clear resizing policy, and plan to get it adjusted after the proposal.
UK size L is equivalent to a US size 6, with an inner diameter of 16.5mm. Use the full conversion chart above for all other size equivalents.
UK size N converts to a EU size 54, with an inner diameter of 17.3mm. If you’re buying from a European jeweller, it’s worth checking the diameter alongside the EU number, since EU sizing is based on circumference in millimetres rather than a letter or number scale. Use the full conversion chart above for any other UK-to-EU equivalents.
UK ring sizes use letters, while the US uses numbers – a UK size L, for example, is a US size 6. The simplest way to convert is to find your UK letter in the chart above and read across to the matching US number. If you only have a diameter or circumference measurement in millimetres, you can use that directly to find your US size without needing to work out your UK size first.
Now you know your size, the exciting part begins. Bridebook connects you with trusted jewellers and engagement ring specialists across the UK, alongside everything else you need to plan your wedding from proposal to reception.
Sign up now and get ready to plan your wedding!

Bridebook is the world’s #1 wedding planning platform, used by over 2.8 million couples. Our content is informed by real data from the Bridebook UK Wedding Report, which draws on responses from thousands of couples planning their weddings each year. Where expert input is included, contributors are named and their credentials verified. We update our articles regularly to ensure prices, statistics, and advice reflect current market conditions.
