UK Ring Size Conversion Calculator & Table – 2025 (UK, US, EU)

Getting your ring size right is one of the most important steps when buying jewelry. A ring that’s too loose can easily slip off and get lost, while one that’s too tight is uncomfortable and difficult to remove.

On this page, you will find our free UK ring size conversion calculator to help you convert your UK ring size to all other international ring size regions. This will help you choose the correct ring size from any online jewelry store, without any worries.

UK Ring Size Conversion Calculator

To use the UK Ring Size Conversion Calculator, simply select your UK ring size from the dropdown bar below, and see the equivalent units for Europe, the US, and Asia, among other regions.

If you know your ring size in a different format, you can use our other dedicated conversion tools. We have calculators based on the US (Numerical), EU (Circumference), Japanese, and Swiss standards.

Once you have found your perfect size, we invite you to view our list of handmade silver filigree rings and silver opal rings.

UK Ring Size Conversion Table

UK & Australia	US & Canada	EU (Circumference in mm)	Japan, China & S. America	Switzerland
A	0.5	37.5	0.5*	<0*
A ½	0.75	38.2	0.8*	<0*
B	1	38.9	1	<0*
B ½	1.25	39.5	1.5*	<0*
C	1.5	40.2	2	0.2
C ½	1.75	40.8	2.5*	0.8
D	2	41.5	3	1.5
D ½	2.25	42.1	3.5*	2.1
E	2.5	42.8	4	2.8
E ½	2.75	43.4	4.5*	3.4
F	3	44.1	5	4.1
F ½	3.25	44.7	5.5*	4.7
G	3.5	45.4	6	5.4
G ½	3.75	46.0	7	6.0
H	4	46.7	8	6.7
H ½	4.25	47.3	8.5*	7.3
I	4.5	48.0	9	8.0
I ½	4.75	48.6	9.5*	8.6
J	5	49.2	10	9.2
J ½	5.25	49.9	10.5*	9.9
K	5.5	50.5	11	10.5
K ½	5.75	51.2	11.5*	11.2
L	6	51.8	12	11.8
L ½	6.25	52.5	12.5*	12.5
M	6.5	53.1	13	13.1
M ½	6.75	53.8	13.5*	13.8
N	7	54.4	14	14.4
N ½	7.25	55.1	14.5*	15.1
O	7.5	55.7	15	15.7
O ½	7.75	56.4	15.5*	16.4
P	8	57.0	16	17.0
P ½	8.25	57.6	16.5*	17.6
Q	8.5	58.3	17	18.3
Q ½	8.75	58.9	17.5*	18.9
R	9	59.6	18	19.6
R ½	9.25	60.2	18.5*	20.2
S	9.5	60.9	19	20.9
S ½	9.75	61.5	19.5*	21.5
T	10	62.2	20	22.2
T ½	10.25	62.8	21	22.8
U	10.5	63.5	22	23.5
U ½	10.75	64.1	22.5*	24.1
V	11	64.7	23	24.7
V ½	11.25	65.4	23.5*	25.4
W	11.5	66.0	24	26.0
W ½	11.75	66.7	24.5*	26.7
X	12	67.3	25	27.3
X ½	12.25	68.0	25.5*	28.0
Y	12.5	68.6	26	28.6
Y ½	12.75	69.2	26.5*	29.2
Z	13	69.9	27	29.9
Z ½	13.25	70.5	27.5*	30.5
Z+1	13.5	71.2	28	31.2
Z+2	14	72.5	29*	32.5
Z+3	14.5	73.7	30*	33.7
Z+4	15	74.8	31*	34.8
Z+5	15.5	76.0	32*	36.0
Z+6	16	76.9	33*	36.9

Disclaimer: Values marked with an asterisk (*) are approximated as a direct, standardized equivalent is not available. Values marked as <0* are for sizes that are smaller than the official starting point of the Swiss sizing system and are mathematical extrapolations.

These units were measured based on international ring size standards.

Other Key Factors to Consider for a Perfect Ring Fit

Getting your baseline UK Ring Size Conversion measurement is the first step, but for a truly perfect fit, you need to consider a few other variables. Your finger size isn’t a static number; it’s a dynamic measurement that can be influenced by your body and the ring’s design. Factoring in these details is the pro move that separates a good fit from a great one.

Here are the other critical factors to keep in mind:

• Temperature and Time of Day: Your fingers can swell in the heat and shrink in the cold. To find a reliable average, it’s best to measure your finger at room temperature during the middle of the day. Avoid measuring first thing in the morning when you might have some water retention or after a hot shower.
• Diet and Lifestyle: Consuming a salty meal, alcohol, or engaging in an intense workout can temporarily cause your fingers to swell. For the most accurate reading, measure when your body is in a neutral state.
• The Ring’s Band Width: This is a big one. A wider band (think 6mm or more) covers more of your finger and will fit more snugly than a thin, delicate band of the same size. For these wider styles, it’s a standard rule to go up a quarter or even a half size to ensure a comfortable fit.
• Your Knuckle Size: If you have a larger knuckle, you face a unique challenge. You need a ring that’s big enough to slide over the knuckle but not so big that it spins around once it’s at the base of your finger. In this case, you’ll need to find a size that strikes the perfect balance between the two measurements.

Sizing It All Up: Your Path to the Perfect Fit

Consider yourself officially equipped with a sizing black belt. You’re now armed with the insider knowledge that separates a good purchase from a perfect one. By understanding that your ring size is a dynamic measurement—influenced by everything from the time of day to the width of the ring’s band—you’ve moved beyond the realm of guesswork and into the world of precision. This knowledge is your single best tool for ensuring comfort, security, and peace of mind.

Mastering your fit is especially critical when you’re in the market for a piece as intricate as a filigree ring, where a resizing attempt can be a high-stakes gamble with a work of art. With these factors in mind, you can now browse online collections and custom-order pieces with total confidence.

The nagging fear of a ring that’s too tight or, even worse, one that’s lost, is a thing of the past. With your perfect size locked in through this UK Ring Size Conversion guide, you’re ready for the most exciting part of the journey: finding the ring that feels like it was made just for you.