Engagement Rings
Ring Size Chart: Measurements and US/UK Conversions
Use the diameter and circumference chart as a reference, understand US and UK labels, and confirm the correct ordering size with Glora.
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Use measurements before choosing a size label
Measure the inner diameter of a round ring that fits your intended finger, then compare it with the chart below. Use this as a starting point and confirm your ordering size with Glora Diamonds.
Ring measurements and international sizes
|
Inner diameter (mm) |
Inner circumference (mm) |
US size |
UK size |
|---|---|---|---|
|
14.9 |
46.8 |
4 |
H |
|
15.3 |
48.1 |
4.5 |
I |
|
15.7 |
49.3 |
5 |
J |
|
16.1 |
50.6 |
5.5 |
K |
|
16.5 |
51.8 |
6 |
L |
|
16.9 |
53.1 |
6.5 |
M |
|
17.3 |
54.3 |
7 |
N |
|
17.7 |
55.6 |
7.5 |
O |
|
18.1 |
56.9 |
8 |
P |
|
18.5 |
58.1 |
8.5 |
Q |
|
19.0 |
59.7 |
9 |
R |
|
19.4 |
60.9 |
9.5 |
S |
|
19.8 |
62.2 |
10 |
T |
|
20.2 |
63.5 |
10.5 |
U |
|
20.6 |
64.7 |
11 |
V |
|
21.0 |
66.0 |
11.5 |
W |
|
21.4 |
67.2 |
12 |
X |
Measurements and conversions are rounded reference values from GIA’s international ring size chart. US and UK labels are different sizing systems; confirm which system your seller uses.
How to Measure Your Ring Size at Home
-
Choose a round, undamaged ring that fits the correct finger and hand.
-
Measure straight across its centre, from inside edge to inside edge, in millimetres.
-
Compare the measurement with the inner-diameter column above.
Measure the opening, excluding the metal band. An out-of-round ring will not give a reliable diameter measurement. GIA’s sizing guidance
Quick Tips for a Comfortable Fit
-
Between sizes? Ask for help before choosing.
-
Choosing a wide band? Check the fit using a sizer of similar width.
-
Avoid temperature extremes. Fingers can shrink in the cold and swell in the heat.
-
Check the knuckle. The ring should pass over it comfortably and stay secure on your finger.
Frequently Asked Questions
Can I measure with string or paper?
Only as a rough estimate. These methods can introduce errors and overlook knuckle fit. A proper ring sizer is more reliable.
Does the same chart apply to everyone?
Yes. Measure the specific finger and hand where you intend to wear the ring.
Need Help Choosing Your Size?
Contact Glora Diamonds with your measurement and preferred ring design to confirm the ordering size.
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A little more to discover
How to Measure Your Ring Size at Home – Step by Step
Learn a simple way to estimate finger circumference at home, then check the sizing system and confirm the correct fit before ordering.
Choosing an engagement ring in 2026: a practical checklist
Set a comfortable budget, compare shapes and settings, and confirm the diamond report, hallmark, ring size and written terms before ordering.
A little guidance from Glora
Make your ring-size check easier
Ring Size Chart: Measurements and US/UK Conversions
Use a measurement as a starting point, then confirm the fit for your design.
Use a ring that fits the right finger Open to explore
Measure the inside of a well-fitting ring and note the units. The same person’s fingers can need different sizes.
Check the chart and the band Open to explore
Make sure you are using the same size system as the chart. Share the band width and design when asking the team to confirm your size.
Keep the measurement with your enquiry Open to explore
Send the measurement method, units and product name together. Ask for a fit check before committing to a size.
Illustrations explain what to compare; they do not represent a particular product or its dimensions.