The Real Gem Ring Size Guide

Find Your Perfect Fit

We want your ring to feel as flawless as it looks. Whether you're treating yourself or surprising someone special, our ring size guide will help you find the ideal fit with ease and confidence.

Standard UK & US Ring Sizes

Ring sizes are measured differently across countries, but all sizes relate back to the same thing: the circumference of your finger or the internal diameter of your ring.

Below is the UK to US ring size conversion chart with exact measurements in millimetres.

UK Size	US Size	Circumference (mm)	Diameter (mm)
A	—	37.8	12.0
B	1	39.1	12.5
C	1 ½	40.4	12.9
D	2	41.7	13.3
E	2 ½	42.9	13.7
F	3	44.2	14.1
G	3 ¼	45.5	14.5
H	4	46.8	14.9
I	4 ½	48.0	15.3
J	4 ¾	48.7	15.5
K	5 ¼	50.0	15.9
L	5 ¾	51.2	16.3
M	6 ¼	52.5	16.7
N	6 ¾	53.8	17.1
O	7 ¼	55.1	17.5
P	7 ¾	56.3	17.9
Q	8 ¼	57.6	18.3
R	8 ¾	58.9	18.7
S	9 ¼	60.2	19.1
T	9 ¾	61.4	19.5
U	10 ¼	62.7	19.9
V	10 ¾	64.0	20.3
W	11 ¼	65.3	20.7
X	11 ¾	66.6	21.1
Y	12 ¼	67.8	21.5
Z	12 ¾	68.5	21.8
Z+1	13 ½	70.2	22.4
Z+2	14 ¼	71.4	22.8

Not Sure About Your Size?

Here are a few simple ways to measure:

Option 1: Use a Ring You Already Own

Measure the internal diameter in millimetres.
Match the number to the diameter column in our chart above.

Option 2: Use a Piece of String or Paper

Wrap it around the base of your finger.
Mark where the ends meet and measure in millimetres.
Match that measurement to the circumference column in our chart.

💡 Tip: Measure your finger at the end of the day, when it’s at its largest. Avoid measuring when your hands are cold, as this can give a smaller reading.

Sizing Tips

Rings with thicker bands may feel tighter; consider going up half a size.
Your dominant hand tends to be slightly larger.
Engagement rings typically fit best on the left ring finger.
If you’re between sizes, it’s usually safer to size up.
Most rings can be resized (excluding full eternity bands and some bespoke styles), so you don’t need to worry if it’s not perfect first time.