Pick the tool that matches what you have
Every tool here is free and works in your browser. Start with the one that fits what you have in your hand right now: a ring, a ruler, a printer or only a number from a chart.
Ring size calculator
Enter an inside diameter or finger circumference and get the closest US, UK and EU size, with a note on half sizes and wide bands.
Open the calculator →Printable ring sizer
A print-at-home sizer with a 50 mm check line so you can confirm your printer did not scale it.
Print a sizer →Size conversion chart
US, UK, EU and diameter side by side, for when a seller uses a different scale from the one you know.
See the chart →US to UK converter guide
How US numbers map to UK letters, and where the two scales do not line up exactly.
US to UK →Size by circumference
Wrapped a strip around a finger? Match the circumference to a size.
By circumference →Measure an existing ring
Step by step instructions for reading the size from a ring that already fits.
Measure a ring →Which method is most accurate?
A jeweller's rigid finger gauge is the strongest starting point, because it reproduces a round metal opening and lets you feel the knuckle. After that, measuring a ring that already fits on the same finger is reliable if the ring is round and you measure the empty opening twice. A calibrated printed sizer and a paper strip are useful estimates. String is the least dependable, because it stretches and settles into soft tissue.
Whatever you use, check the result against the width of the band you plan to buy. Wide bands often need a half size or more above a narrow band. Our wide band guide and large knuckle guide cover both cases.
A short routine that works
- Measure at the end of the day, when hands are warm and settled. See the best time to measure.
- Take the measurement twice on two different days.
- Use the calculator to turn the number into a size.
- If the ring is wider than 4 mm, add a half size and read the comfort fit guide.
- Confirm with a jeweller before ordering anything made to order or non-resizable.
Buying a ring as a gift
If you are buying for someone else, see how to find his ring size secretly and the men's wedding ring guide. Choose a seller with a free exchange or resize policy.