Ring Size Converter
Enter your ring size and instantly convert between UK, US and EU sizes and the inner diameter in mm.
How to use
- Enter your value in the box above or pick an option.
- The result updates live — no button to press.
- Change the value or unit and the new result appears automatically.
Note
Sizes are matched to the closest row of the standard international chart. The EU size is simply the circumference in mm. Fingers can swell a little in the evening — always double-check the size and confirm with a jeweller if in doubt.
Frequently Asked Questions (FAQ)
What does the ring size converter do?
It converts a ring size between UK, US and EU sizes and shows the inner diameter in mm.
How do I measure my size?
Wrap a thread around your finger to measure the finger circumference in mm, or enter a size you already know.
How accurate is the conversion?
Sizes are matched to the closest row of the standard international chart, and fingers can swell a little in the evening - the tool advises confirming the size with a jeweller.
Is the EU size different from the others?
The EU size is simply the circumference in millimetres, so it matches what you measured around your finger.