Ring Size Chart & Converter

Ring size chart and converter for every country

Ring sizes are measured differently around the world: the US and Canada use numbers with quarter sizes, the UK and Australia use letters, India, China and Japan use whole numbers on finer scales, and Europe uses the inside circumference in millimetres (ISO 8653). This ring size chart converts between all of them from one exact measurement, and helps you find your size in the first place with a printable ring sizer and an on-screen sizer you can calibrate.

Choose the system you know, pick your size, and every other system updates together with the inside diameter and circumference in millimetres and inches. If you have no size at all, wrap a strip of paper round your finger and type the length, or place a ring that fits on the calibrated on-screen circle.

Everything is drawn and calculated in your browser. Remember that brands differ by up to half a size, so when you buy from a particular jeweller, compare its own chart in millimetres.

How to use the Ring Size Chart & Converter

1. Pick the system under I know my size in and choose your Size. Or choose a diameter, circumference or inch option and type a measurement.
2. Read the matching US, UK, India, China/Japan, EU and Swiss sizes, and the exact millimetres.
3. No size yet? Use Measure on screen: drag the slider until the outline matches a bank card held against the screen, then match the circle to the inside of a ring that fits and press Use this size above.
4. Or print the Printable ring sizer: choose paper and labels, press Download PDF or Print, print at 100% and check the 50 mm square.
5. Cut out the strip, wrap it snugly round the base of your finger, and read the size at the arrow — or lay a ring on the circles.

Ring Size Chart & Converter features

How ring sizes are defined

• US and Canada: inside diameter = 11.63 mm + 0.8128 mm × size, so each whole size adds 0.81 mm of diameter (about 2.55 mm of circumference). US 7 is 17.3 mm across.
• UK, Australia, New Zealand, Ireland: letters from A under British Standard BS 6820, where size C is 40 mm round; each letter adds 1.25 mm of circumference, with half sizes between letters and Z+1, Z+2… above Z. N½ is about 54.4 mm round.
• India: the chart Indian jewellers publish runs from size 1 (about 13.1 mm across, 41 mm round) to 30 (about 22.2 mm), in uneven steps that follow US quarter sizes; India 14 is US 7. Brands can differ by half a size, so check their millimetres.
• Japan and China: size 1 is 13 mm across and each step adds a third of a millimetre — roughly 1 mm of circumference.
• Europe (ISO 8653): the size is simply the inside circumference in millimetres — 54 means 54 mm. Switzerland, Italy and Spain use the same measurement minus 40 (so 14).

Getting an accurate measurement

Fingers are larger in the evening and in warm weather, and smaller when cold, so measure at the end of the day at room temperature. Measure the finger the ring will go on — the dominant hand is often half a size larger. If your knuckle is much wider than the base of your finger, choose a size that slides over the knuckle. Wide bands (6 mm and more) fit tighter: go up a quarter to half size. A strip of paper should be snug but slide over the knuckle; mark where it overlaps and measure the length against the printed millimetre scale or a printable ruler.