Ring Size Converter
Convert ring sizes between US, UK, EU, and Japan — or enter your finger's inside diameter (mm) to find your size.
Convert by size
Convert by measurement
How to measure your ring size at home
Method 1: Measure an existing ring
Take a ring that fits the finger you're sizing. Use a ruler to measure the inside diameter (the widest distance across the inside of the band) in millimeters. Enter that number above.
Method 2: String + ruler
Wrap a non-stretchy string or strip of paper around the base of your finger. Mark where it overlaps. Lay it flat and measure the length in millimeters — that's your finger circumference.
Tip
Measure at the end of the day when fingers are slightly swollen. This is your true size. Avoid measuring in cold weather or right after exercise.
Frequently asked questions
What's a US size 7 in UK?
A US size 7 ring is approximately a UK size N (or N½). UK ring sizes use letters that increase by half-sizes.
What's a US size 7 in EU?
A US size 7 is approximately an EU size 54 (or 17.3mm inside diameter). EU sizes use the circumference in millimeters.
My finger is between sizes — what do I do?
Always round up to the larger size, especially for wider bands. A wider band feels tighter than a thin band at the same size.
Are men's and women's ring sizes different?
The sizing system is the same — sizes are just numbers. Men's rings tend to be larger (US 9-13) and women's smaller (US 5-8), but the conversion is identical.