What is a UK size X ring in US sizes?

US 12. On the GIA chart a UK X is 67.2mm around the inside, which is the same row as US 12.

How many millimetres is ring size X?

67.2mm around the inside and 21.4mm across. European and ISO sizes are the circumference rounded to the millimetre, so it is a 67.

What is between size X and size Y?

X½, at 67.9mm. Each half size adds about 0.7mm to the circumference and each full letter about 1.3mm, which is why a ring that is close but not right is usually a half size out rather than a whole one.

Is X a small or a large ring size?

It sits towards the larger end of the A to Z scale. A size is a measurement rather than a judgement, and the only way to know it is to measure the finger the ring is for.

Should I size up for a wide band in size X?

Often by a half size. A wide band covers more of the finger, so it can feel snugger than a narrow ring at the same marked size. Measure with a gauge close to the width you are buying, and our size finder explains how.

Ring sizes

UK ring size X

A UK X is a US 12 and an EU 67: 67.2mm around the inside of the ring and 21.4mm across it.

US and Canada: 12
EU and ISO: 67
Circumference: 67.2mm
Diameter: 21.4mm
Japan and Asia: 25
Switzerland: 27½

Size X and the half sizes either side

UK sizes go up in half letters, each about 0.7mm around. If X is nearly right, the answer is usually the half size next to it rather than a whole letter away.

UK X with its neighbours, from the GIA conversion chart
UK	US	EU / ISO	Circumference	Diameter
W	11.5	66	66mm	21mm
W½	11.75	67	66.6mm	21.2mm
X	12	67	67.2mm	21.4mm
X½	12.25	68	67.9mm	21.6mm
Y	12.5	69	68.5mm	21.8mm

What a band weighs in size X

A bigger size takes more metal, so the same ring weighs a little more in a larger size. These are the weights of a plain court band at 67.2mm, the inside of a size X, at four widths.

Estimated grams, plain court band, UK X, 1.6mm wall
Metal	2mm	4mm	6mm	8mm
Titanium	0.9g	1.8g	2.7g	3.6g
Zirconium	1.3g	2.6g	3.9g	5.2g
9ct yellow gold	2.3g	4.5g	6.8g	9.1g
18ct yellow gold	3.1g	6.2g	9.4g	12.5g
Platinum 950	4.0g	8.0g	12.0g	16.0g

Estimates from the model in our ring weight calculator, using the same reference alloys. A finished ring with a pattern, stone or different wall thickness will differ.

Rings made in size X

All 99 of our wedding bands are made to order in size X, in every width and finish they come in. Size is chosen on the ring's page, and if you are not sure yet you can order with "I do not know yet" and we confirm it with you before anything is made. The diamond solitaires are set in UK F to T, so a size X engagement ring is not one we can make.

Wedding rings · Engagement rings · Find your size at home · Finding a size secretly

Size X questions

What is a UK size X ring in US sizes?: US 12. On the GIA chart a UK X is 67.2mm around the inside, which is the same row as US 12.
How many millimetres is ring size X?: 67.2mm around the inside and 21.4mm across. European and ISO sizes are the circumference rounded to the millimetre, so it is a 67.
What is between size X and size Y?: X½, at 67.9mm. Each half size adds about 0.7mm to the circumference and each full letter about 1.3mm, which is why a ring that is close but not right is usually a half size out rather than a whole one.
Is X a small or a large ring size?: It sits towards the larger end of the A to Z scale. A size is a measurement rather than a judgement, and the only way to know it is to measure the finger the ring is for.
Should I size up for a wide band in size X?: Often by a half size. A wide band covers more of the finger, so it can feel snugger than a narrow ring at the same marked size. Measure with a gauge close to the width you are buying, and our size finder explains how.