Understanding Ring Size Standards
EU Ring Sizes Explained (EU to UK & US)
EU sizes use the inner circumference measurement in mm. Use the conversion chart below to switch EU numbers to UK letters and US numbers.
Convert EU to UK (numbers to letters)
Find your EU size, read across to the UK letter (e.g. EU 54 to UK N).
We round to the nearest quarter or half size.
Convert EU to US Ring Sizes
The same row shows the US size (e.g. EU 54 to US 7).
Measuring EU sizes (mm)
Measure diameter at room temperature; wider bands feel tighter.
US Ring Sizes Demystified (American to UK & EU)
US sizes are numeric with half or quarter steps. Use the chart to convert US numbers to UK letters and EU numbers.
Convert US to UK (numbers to letters)
Look up your US size and read across to the UK letter (e.g. US 7 to UK N), mapped to the closest UK quarter.
Convert US to EU Ring Sizes
See the EU circumference (mm) alongside your US size; ideal if you’ve measured a ring’s diameter.
US halves & quarters
Systems don’t align 1:1; the chart picks the closest comfortable quarter.
UK Ring Sizes and Their Unique Aspects (Letters A–Z+)
The UK uses letters (with halves). Most women’s sizes sit H–Q; many men’s M–Z.
Convert UK to US (letters to numbers)
Find your UK letter and read across to the US number (e.g. UK M → US 6½).
Convert UK to EU (letters to mm)
The same row shows EU circumference (mm) to verify against a measured diameter.
Getting an accurate UK fit
Consider the band width and profile of the ring you are sizing for. If you are between sizes on a wide band, go slightly larger as a wide band will feel tighter on the finger.
How do you measure your ring size correctly?
If you are measuring your own finger size with a ring sizer it’s important to know how to do it correctly, particularly if you are using an adjustable ring sizer. This is because it’s easy to adjust the ring sizer behind your knuckle to what feels comfortable, but then forget that you need to be able to get the ring over your knuckle. This is why I recommend borrowing one of my proper ring sizing kits. You can try on fixed size rings which eliminate the danger of choosing the wrong size.
If you are sizing your finger at home I would always recommend to check your size at different times of the day, because your fingers will be slightly smaller when you wake up I the morning than they will be later on in the day. Choose a size which feels comfortable, but isn’t too loose to slip of when your hands are cold or wet.
If you need any assistance in choosing the perfect ring size, I’m always happy to help.