UK Ring Size vs US Ring Size Conversion Chart
Buying a ring online should be exciting — not stressful.
But if you’ve ever shopped across borders, you’ve probably run into this common issue:
UK ring sizes use letters (J, K, L…), while US ring sizes use numbers (5, 6, 7…).
So what happens when you fall in love with a ring from a UK brand, but you only know your US size (or the other way around)?
This guide makes it simple. You’ll find:
- A clear UK to US ring size conversion chart
- The most common UK–US size equivalents
- How to measure your ring size correctly (so you don’t have to guess)
- A helpful FAQ section for quick answers
UK Ring Size vs US Ring Size: What’s the Difference?
The UK and US use two different sizing systems:
- UK ring sizes are labeled with letters (F, G, H, I, J, K, L…)
- US ring sizes are labeled with numbers (3, 4, 5, 6, 7…)
Both systems are based on the same thing:
the inner circumference (mm) or inner diameter (mm) of the ring.
They just display it differently.
UK to US Ring Size Conversion Chart (Most Common Sizes)
Below is one of the most useful UK to US ring size conversion tables.
It covers most sizes for women’s rings, men’s rings, engagement rings, and wedding bands.
Tip: Some brands may vary slightly (about 0.25–0.5 size). If you’re between sizes, always check the millimeter measurements.
UK Ring Size vs US Ring Size Chart
| UK Size | US Size | Circumference (mm) | Diameter (mm) |
|---|---|---|---|
| F | 3 | 44.2 | 14.1 |
| G | 3.5 | 45.5 | 14.5 |
| H | 4 | 46.8 | 14.9 |
| I | 4.5 | 48.0 | 15.3 |
| J | 5 | 49.3 | 15.7 |
| K | 5.5 | 50.6 | 16.1 |
| L | 6 | 51.9 | 16.5 |
| M | 6.5 | 53.1 | 16.9 |
| N | 7 | 54.4 | 17.3 |
| O | 7.5 | 55.7 | 17.7 |
| P | 8 | 57.0 | 18.1 |
| Q | 8.5 | 58.3 | 18.5 |
| R | 9 | 59.5 | 18.9 |
| S | 9.5 | 60.8 | 19.4 |
| T | 10 | 62.1 | 19.8 |
| U | 10.5 | 63.4 | 20.2 |
| V | 11 | 64.6 | 20.6 |
| W | 11.5 | 65.9 | 21.0 |
| X | 12 | 67.2 | 21.4 |
| Y | 12.5 | 68.5 | 21.8 |
| Z | 13 | 69.7 | 22.2 |
Quick UK to US Ring Size Guide (Easy to Remember)
If you don’t want to look up a chart every time, here’s a simple shortcut:
- UK J ≈ US 5
- UK L ≈ US 6
- UK N ≈ US 7
- UK P ≈ US 8
- UK R ≈ US 9
- UK T ≈ US 10
- UK V ≈ US 11
- UK X ≈ US 12
How to Measure Ring Size Correctly (So You Don’t Order the Wrong Size)
Most ring sizing mistakes happen because of measurement errors — not because the chart is wrong.
Here are the 3 most reliable methods.
Method 1: Measure an Existing Ring (Most Accurate)
This is the easiest and most accurate way if you already own a ring that fits well.
- Pick a ring that feels comfortable
- Measure the inside diameter in millimeters
- Match it to the chart above
Method 2: Measure Your Finger Circumference (If You Don’t Have a Ring)
- Wrap a soft measuring tape around your finger
- Make sure it’s snug but not tight
- Record the circumference in mm
- Match it to the chart
Pro tip: Measure in the evening. Fingers tend to swell slightly later in the day.
Method 3: Use a Printable Ring Sizer
Many jewelry brands offer printable ring sizing guides.
Just make sure:
- You print at 100% scale
- You verify accuracy using a credit card width reference
FAQ: UK Ring Size to US Ring Size
What is UK ring size K in US?
UK size K is approximately US 5.5.
What is UK ring size N in US?
UK size N is approximately US 7.
What is UK ring size O in US?
UK size O is approximately US 7.5.
Why does UK to US ring size conversion sometimes vary?
Small differences can happen because:
- Brands may use slightly different sizing standards
- Wider bands fit tighter (you may need to size up 0.5)
- Finger swelling changes throughout the day
Should I size up or down for an engagement ring or wedding band?
If you’re between two sizes, it’s usually safer to go slightly larger.
A ring that’s too tight can be uncomfortable and hard to remove, while a slightly loose ring can often be adjusted with a ring guard or resizing.
