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 Ring Size Chart UK to US Ring Size Conversion


Finger Size Chart UK to US and European Measurements 


Find the perfect ring size 


Our perfect size service is refundable and ensures 100% correct measurement. 


Place an Order with the UK or US sizing.


Did you know we can create any of our ring designs by ordering in either a UK or US size convention? In the UK, we work to a letter system. Conversely, US jewellers work to a number system. In both systems, the smaller the number or letter the smaller the size. Many buyers struggle with how the UK and US measurements relate to each other. For this reason, our chart provides an easy-to-use conversion from one system to another. But, please order by either system online or with our friendly team of experts. 

Find Your Correct Ring Size - Get the Perfect Fit - Measure your ring finger at home.


For most wedding rings and engagement rings, we measure the third finger of the left hand (not the middle finger) using our ring sizers available at Serendipity Diamonds. 

Use our conversion table below for the US to UK sizes. With exceptional customer service, our small and friendly team remain on hand to help with any questions. With our expert help, we aim to ensure your ring has the perfect fit. Talk to us about the size of any precious metal ring and how to obtain accurate measurements for your ring. 

Refer to our international chart in the lower section of this page for an accurate conversion from the UK to US or EU ring sizes. We have included the internal diameter in mm. for most ring sizes. Our ring size converter works for both Wedding Rings and Engagement Rings.  

Use our perfect size service


You will notice that all of the rings on our website feature a button to our ring size service available in our showroom or to use at home. Unlike other systems, each size sample comes as a loose band making it easy to try. Please note that this service forms part of your order if needed. 


UK ring sizes to US sizes

Owing to our website showing UK finger sizes, please feel free to look at the size stick which shows UK equivalents to US sizes. We have included this due to the variation of opinion between many conversion charts. If there is no clear equivalent size – contact us – we will be happy to work to the US finger size when we create your ring.  


Free Advice - Call or Email

Please scroll down for a full-size conversion chart.

Please remember that some ring designs cannot be re-sized for various reasons. Full eternity rings are the most obvious example of rings that cannot be adjusted by size. Engagement rings with tension style settings are unsuitable for significant size alterations. Claw settings make the most popular style purchased without any finger size uncertainty. Claws or prongs can be re-tensioned around the Diamond following size adjustments to ensure the stone's security. If you are uncertain about finger size, please feel free to contact us anytime for additional guidance. 


Guidance on Typical Finger Sizes

To better understand how different sizes compare, the following information assigns sizes to small, average ring sizes and large finger sizes. If you cannot take a specific size reading, this information might help you select a size close to the correct finger size. Your ring will likely need less of an adjustment on the next purchase. We can help with any size adjustments in the future after purchase. 


  • Sizes G - I Tiny sizes
  • Sizes J - K Typical for smaller hands
  • Sizes L - N Mid / average sizes
  • Sizes O - P Slightly larger sizes
  • Sizes Q - T Larger finger sizes
  • Sizes T - Z Substantial sizes


Size Charts

The chart below gives some guidance on conversion. Please remember that we can work to in-between finger sizes. Our website allows a full or half size to be chosen. We can apply further increments by contacting us before or after placing your order. For example, you might need size L and a quarter (a quarter of a size larger than L). In this instance, a size L and a quarter equals a US size 6. This is no problem to apply if you contact us before or after placing your order. We gladly offer help with any ring size conversion needed. 


Help, I have no idea!

If you don't know your partner's finger size, we can choose a suitable 'guesstimate' for the ring. Since we provide a free size adjustment for most ring styles, altering will not be a problem. Please see our terms and conditions for which styles are not included in the free resize. Please note that some ring size conversion charts vary by modest amounts. For some clients who borrow a ring from their partner, worn on the same finger, we can use the mandrel, size stick or Wheatsheaf to assess the size. 

International Ring Size Chart


The following chart provides every permutation to translate the correct finger size. This is a ring size guide to convert from UK to US sizes. It is also a chart for the US to the UK. Choose your local size, and then look up the inside diameter. Use the diameter measurement to calculate circumference using easy-to-use formulae. 


Circumference calculators feature online for anyone looking to work out this measurement. Use our chart to find the correct local size required. 

American British European Inside Diameter (mm)
A 12.065
38 12.096
12.263
1 12.344
39 12.344
B 12.459
12.657
40 12.733
12.751
C 12.852
41 13.051
2 13.157
D 13.246
42 13.369
13.444
13.564
E 13.640
43 13.687
13.838
3 13.970
44 14.006
F 14.034
14.232
45 14.324
14.376
G 14.427
14.625
46 14.642
4 14.783
H 14.821
47 14.961
15.019
15.189
I 15.215
48 15.279
15.413
5 49 15.597
J 15.608
15.806
50 15.916
K 16.002
16.200
51 16.234
6 L 16.396
52 16.552
16.594
M 16.789
16.815
53 16.871
16.988
N 17.183
54 17.189
7 17.221
17.381
55 17.507
O 17.577
17.628
17.775
56 17.826
P 17.971
8 18.034
57 18.144
18.169
Q 18.364
18.453
58 18.462
18.562
R 18.758
59 18.780
9 18.872
18.956
60 19.098
S 19.152
60 19.098
19.279
19.350
61 19.416
T 19.545
19.741
10 19.761
U 19.939
63 20.054
20.137
10½ 20.168
V 20.333
64 20.372
20.531
11 20.599
65 20.690
W 20.726
20.925
11½ 66 21.008
X 21.120
21.318
67 21.326
12 21.412
Y 21.514
68 21.645
21.712
12½ 21.819
Z 21.908
69 21.963
22.106
13 22.252

How do you find out ring size from circumference.


Measure the circumference of a ring; if you need to find out the diameter and ring size, use a simple calculator. Some clients obtain their partner's ring (perhaps an existing ring) to measure the diameter. Next, they work out the outer circumference of the ring. 


As part of our work, we use an online circumference-to-diameter calculator to determine diameter. Using this system, convert circumference to diameter. Once you have your diameter, check against the size conversion chart above. 

Is there such a thing as a downloadable ring chart?


Some websites provide a downloadable ring chart showing finger sizes. PDF charts provide a convenient way to download and print information for home use. Some charts provide ring outlines to place an existing ring to estimate the size. The Multisizer tool helps you measure your ring size in UK and US size systems. Take care when using printable diagrams to ensure sizes are to scale. 

Sizers for Men's rings 


For men's wedding rings, we provide a choice of ring size samples to try on a variety of sizes. As part of our perfect service, after you approximate size with a Multisizer, we send out the three nearest size samples in full and half sizes to narrow down your correct ring size. 


The above video explains exactly how our service works.