Ring Size Conversion Guide

Use this ring size conversion chart to compare UK, US and EU ring sizes, alongside internal diameter and circumference measurements in millimetres.

Ring sizing can vary slightly between jewellers, ring styles and measuring tools, so this chart should be used as a guide rather than an absolute guarantee. Wider rings, signet rings and heavier bands can feel tighter than fine rings in the same size.

If you are ordering a made-to-order or bespoke ring from Aeternum Jewellery and are unsure which size to choose, contact us before placing your order.

 

UK size	US size	EU size	Inside diameter (mm)	Inside circumference (mm)
F	3	44	14.1	44.2
G	3.5	45	14.4	45.5
H	4	46.5	14.8	46.8
I	4.5	48	15.2	48.0
J	5	49	15.6	49.3
K	5.5	50.5	16.0	50.6
L	6	51.5	16.4	51.9
M	6.5	52.5	16.8	53.1
N	7	54	17.2	54.4
O	7.5	55	17.6	55.7
P	8	56.5	18.0	57.0
Q	8.5	57.5	18.4	58.3
R	9	59	18.8	59.5
S	9.5	60.5	19.2	60.8
T	10	61.5	19.6	62.1
U	10.5	63	20.0	63.4
V	11	64	20.4	64.6
W	11.5	65	20.8	65.9
X	12	66.5	21.2	67.2
Y	12.5	68	21.6	68.5
Z	13	69	22.0	69.7
Z+1	13.5	70.5	22.4	71.0
Z+2	14	72	22.8	72.3
Z+3	14.5	73	23.2	73.6
Z+4	15	74.5	23.6	74.8

 

Choosing the right ring size

The best way to find your ring size is to have your finger measured professionally. If you are measuring at home, measure more than once and avoid measuring when your hands are very cold or warm, as finger size can change throughout the day.

For wider rings, signet rings and heavier bands, some customers prefer a slightly larger size for comfort. If you are unsure, it is better to check before placing your order.

Further guidance

If you are choosing a ring for long-term wear, metal, width and fit all matter. You may also find our Jewellery Materials Guide and Jewellery Care Guide useful when choosing between sterling silver, gold and other precious metals.

For custom sizing, altered proportions or a piece with specific requirements, visit our Bespoke Jewellery page.