Ring Size Converter
US, UK, EU sizes and millimetres โ plus how to measure at home.
About this converter
Pick your system and size; read the equivalents in all four โ US numbers, UK letters, EU (which is simply the inner circumference in millimetres) and the inner diameter. The full chart highlights your row for sanity-checking against a jeweller's table.
Measuring at home, honestly
Two methods that actually work. With a ring that fits: lay it on a ruler and read the inside diameter in millimetres โ the chart column does the rest. Without one: wrap a strip of paper snugly around the finger, mark the overlap, measure the length โ that IS the EU size directly. The craft in the details: measure in the evening (fingers swell through the day and shrink in cold), size for the knuckle if it's the widest point, round up between sizes, and expect wide bands to wear about half a size tighter. Buying as a surprise has one reliable trick โ borrow a ring from the same finger of the same hand, because fingers differ by whole sizes. Resizing exists, but sizing right beats it: most rings resize one or two sizes at most, and some (eternity bands, tension settings) can't. Shoe sizes and general units follow the same convert-through- millimetres philosophy elsewhere on the site.
Frequently asked questions
How do I measure my ring size at home?
Wrap a paper strip snugly around the finger, mark where it overlaps, and measure the length in mm โ that's your EU size, and the chart converts it. Or measure a fitting ring's inner diameter on a ruler.
What's the most common ring size?
Women's rings cluster around US 6-7 (EU 52-54); men's around US 9-10 (EU 59-62). Useful as a surprise-gift prior, but fingers vary too much to guess by demographics alone.
Should I size up or down between sizes?
Up โ a slightly loose ring goes on and off; a tight one is misery. Wide bands wear tighter, so go up half a size for those anyway.
When during the day should I measure?
Evening, at normal temperature โ fingers are smallest on cold mornings and largest after heat or salt. Measure two or three times across days for a confident answer.