Ring Size Converter
Ordering a ring from overseas? Enter your US ring size and see the equivalent UK, EU, diameter, and circumference measurements.
How Ring Sizing Systems Work
US ring sizes are numerical, starting around size 3 (small) and going up to size 13 or higher (large). Each full size represents an increase of about 0.8 millimeters in diameter, or roughly 2.5 millimeters in circumference.
UK sizes use letters instead of numbers. A US size 7 is a UK size N. The letter system can be confusing, but it's standard across the UK, Ireland, and Australia. Half sizes exist between most letters.
European sizes are numerical like US sizes but on a different scale. They're based on the inner circumference in millimeters multiplied by a conversion factor. A US size 7 converts to approximately EU 54.
Accurate At-Home Measurement
If you don't have a ring sizer, use a piece of string or a thin strip of paper. Wrap it around the base of your finger, where the ring will sit. Mark where the end meets the rest of the string, then lay it flat and measure the length in millimeters. That's your finger's circumference.
Match the circumference to a size chart, or use this calculator's output. If your circumference is 54 mm, look for the size that matches that measurement. In the US, that's typically a size 7.
Measure the finger you'll actually wear the ring on. Fingers on your dominant hand are often slightly larger. Measure a few times to ensure consistency, and don't pull the string too tight or leave it too loose—it should slide over your knuckle with slight resistance.
Tips for Buying Rings Online
If you already own a ring that fits, measure its inside diameter with a ruler. Lay the ring flat and measure straight across the inside. Compare that diameter to a chart, or use this calculator in reverse (input the diameter to find the size).
When ordering from international sellers, always check their size chart. Some European sellers use their own numbering systems that don't match standard conversions. Confirm which sizing standard they're using before you order.
Consider the ring's width. Rings wider than 6mm should be ordered half a size larger because they cover more of your finger and feel tighter. Ask the seller if they recommend sizing up for wide bands.
Frequently Asked Questions
How do I measure my ring size at home?
Wrap a string around your finger, mark where it overlaps, then measure the length. That's your circumference. Compare it to a size chart, or use this calculator's circumference output to find your size.
Should I measure my finger at a certain time of day?
Yes. Fingers swell in heat and shrink in cold. Measure at the end of the day when your finger is warmest and slightly swollen. That ensures the ring won't be too tight.
Do ring sizes differ between men and women?
No. Ring sizes are based solely on finger diameter, regardless of gender. A men's size 10 and a women's size 10 are the same physical size.
Why do some rings fit differently even in the same size?
Wide bands feel tighter than thin bands because they cover more of your finger. If you're buying a band wider than 6mm, consider going up half a size.
Can I resize a ring if I get the wrong size?
Most metal rings can be resized up or down by a jeweler, usually by one or two sizes. Eternity bands (stones all the way around) and some materials like tungsten can't be resized.