EU ring size to UK ring size
Enter the EU size to get the UK letter before ordering from a British or Australian store.
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How to use it
- Enter eu size.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Half-size step = (circumference − 37.5) ÷ 0.625, rounded, then mapped to letters: A = 37.5 mm and each letter adds 1.25 mm.
Example
Inputs: EU size = 54 mm. Result: UK size: N; US size: 6.75; Inner diameter: 17.19 mm.
Limits and caveats
- Sizes are rounded to the nearest step of each system, and shop mandrels can differ slightly.
Questions about this tool
What is EU 54 in UK sizes?
It matches UK N, which is 53.75 mm around.
What is EU 52?
It lands on L½, which is 51.875 mm around.
Why do store charts differ slightly?
Some round the figures or use old mandrels; the gap is usually within half a size.