Ring Size Calculator
Free toolMeasure your finger's circumference (with a piece of string or a strip of paper, then a ruler) or the inner diameter of a ring that already fits well. Enter the value in millimeters and we calculate your size in the EU, ES, UK and US systems.
How do I measure my size?
Wrap a piece of string or a strip of paper around the base of your finger, mark where it overlaps, and measure that length with a ruler: that is the circumference in millimeters. If you would rather use a ring that already fits well, measure its inner diameter with a ruler.
Your size
| EU | ES | UK | US |
|---|---|---|---|
How to use it
- Measure the circumference of the finger with a strip of paper, or the inner diameter of a ring that fits well.
- Enter the measurement in millimetres.
- Read the size in the EU, ES, UK and US systems.
What it works out and how
A ring size is defined by its inner circumference. If you enter the diameter, the tool converts it by multiplying by pi. For reference, a circumference of 54.4 mm, which is a diameter of 17.3 mm, equals EU 54, ES 17, US 7 and UK J. The European system matches the circumference in millimetres.
Frequently asked questions
When is the best time to measure?
At the end of the day and with warm hands. Fingers shrink in the cold and can be swollen in the morning.
What if I am between two sizes?
Pick the larger one, especially for wide bands, which fit tighter. Also check that it goes over the knuckle.
How do I find someone else's size without them knowing?
Use a ruler to measure the inner diameter of a ring they wear on that same finger and enter it in millimetres.