Donaldson R F Ring Size Converter
Convert a ring size between UK letters, US numbers and EU sizes, or find it from your finger's circumference or a ring's inner diameter.
Ring size chart
How to measure your ring size
Wrap a thin strip of paper or a piece of string around the base of your finger, mark where it overlaps, and measure the length in millimetres: that is your circumference. Measure at the end of the day, when fingers are largest, and check that the ring will pass over your knuckle. If you are between sizes, choose the larger one; wider bands fit more tightly than thin ones. Or measure the inside width of a ring that fits you and use the inner diameter option.
UK sizes are letters from A upwards (each letter is about 1.25 mm of circumference, with half sizes in between). US sizes are numbers, and EU sizes are simply the inner circumference in millimetres. Jewellers' charts differ by up to half a size, so treat the results as a close guide.