How do I convert my US ring size to UK or EU?

There's no direct formula between systems, so a conversion table is needed. As a reference, US size 6 is approximately UK L½ and EU 51.8mm circumference; US size 10 is approximately UK T½ and EU 62.1mm.

What is the most universal ring size measurement?

The inside diameter or circumference in millimetres. Unlike US numeric sizes or UK alphabetic sizes, millimetre measurements are consistent across all systems and manufacturers.

Can I measure my ring size at home without a sizer?

Yes, approximately. Measure the inside diameter of a ring that already fits, or wrap a strip of paper or string around the base of your finger and measure the length. For a ring you intend to wear long-term, an in-person or professionally guided measurement is more reliable.

Ring Size Conversion Chart: US, UK, EU & MM

Why This Is Confusing

If you've bought rings before in the US, UK, Europe, or elsewhere, the size on your old ring or your "known" size doesn't transfer directly to a new one here — the systems measure different things and aren't related by a simple formula. The US and Canada use an arbitrary numeric scale. The UK, Ireland, and Australia use an alphabetic scale. Most of Europe sizes by the ring's actual inside circumference in millimetres, which is why European sizes look like numbers in the 50s and 60s. The one measurement that's universal across all of them is the millimetre figure, which is why we always ask for it directly if you have it.

Conversion Chart

Inside diameter (mm)	US / Canada	UK / Australia	EU (approx.)
14.9	4	H	—
15.7	5	J½	—
16.5	6	L½	51.8
16.9	6½	M½	53.1
17.3	7	N½	54.4
17.7	7½	O½	55.7
18.1	8	P½	56.9
18.5	8½	Q½	58.2
18.9	9	R½	59.5
19.4	9½	S½	60.8
19.8	10	T½	62.1
20.6	11	V½	64.6
21.4	12	X½	67.2

Conversions are rounded to the nearest standard size and can vary slightly between manufacturers — useful as a reference, not a substitute for an actual measurement when the ring matters. The most requested women's size internationally is around US 6½ (UK M½, roughly 16.9mm), and for men, around US 10 (UK T½, roughly 19.8mm), though hand size varies far more than an average suggests.

How to Measure Without a Sizer

From a ring that already fits: measure the inside diameter straight across the middle in millimetres and match it to the chart.

From your finger: wrap a strip of paper or string snugly around the base of the finger, mark where it overlaps, and measure the length — that's your inside circumference, which you can match against the mm columns above.

A printed ruler alone isn't precise enough for a ring that matters — a millimetre either way is most of a full size. For a bespoke commission, we take a proper in-person measurement during your consultation, or can arrange sizing remotely if you're not yet in Singapore.

What Changes the Size You Actually Need

Band width: wider bands cover more of the finger and fit more tightly. At around 6mm and above, most people need to size up half a size from a narrow band.

Temperature: fingers shrink in cold and swell in heat — measure at normal room temperature, not right after being outdoors in extreme weather.

Time of day: fingers are typically largest later in the day, so measuring in the evening gives the most reliable everyday-wear result.

The knuckle: a ring has to clear it. If your knuckle is noticeably wider than the base of your finger, measure both and choose a size that balances comfort against the risk of it slipping off.

Dominant hand: typically runs slightly larger than the other hand — always measure the specific hand and finger the ring will actually be worn on.

If you're ever between two sizes, the safer choice is usually to size up slightly — a ring that's a touch loose can be resized down; one that won't clear the knuckle can't be worn at all.

Ring Size Conversion Chart: US, UK, EU, and Millimetres