Ring size calculator
Measure your finger or an old ring and get the size in every major system: US, UK, EU, Japan, India and Italy, down to a tenth of a millimetre.
- No sizer? Use a strip of paper and a ruler.
- Have a ring that fits? Lay it on the calibrated on-screen sizer.
- Just converting? Pick "A size".
Measure at the base of the finger, snug but not tight, and make sure the loop would slide over your knuckle.
Enter a measurement to see your size in seven systems at once.
Three ways to find your ring size
Wrap and measure. Wrap a non-stretchy strip of paper around the base of the finger, mark where it overlaps, and measure the length in millimetres. That length is your circumference; type it in above. Our step-by-step measuring guide covers the details that cause most mistakes.
Measure a ring that already fits. Measure straight across the inside of the band, edge to edge, and choose "A ring that fits". Use a ring worn on the same finger and hand; dominant-hand fingers are often a little larger.
Use a sizer. Our online ring sizer draws actual-size circles after you calibrate your screen with a bank card, and the printable ring sizer gives you a paper strip to loop around your finger.
Most common ring sizes at a glance
US whole sizes 4 to 12 with their equivalents. The full international ring size chart goes from US 3 to 16 in quarter sizes.
| US | UK / AU | EU | Japan | Diameter | Circumference |
|---|---|---|---|---|---|
| 4 | H½ | 47 | 7 | 14.9 mm | 46.8 mm |
| 5 | J½ | 49 | 9 | 15.7 mm | 49.3 mm |
| 6 | L½ | 52 | 11 | 16.5 mm | 51.9 mm |
| 7 | N½ | 54 | 14 | 17.3 mm | 54.4 mm |
| 8 | P½ | 57 | 16 | 18.1 mm | 57.0 mm |
| 9 | R½ | 60 | 18 | 18.9 mm | 59.5 mm |
| 10 | T½ | 62 | 20 | 19.8 mm | 62.1 mm |
| 11 | V½ | 65 | 23 | 20.6 mm | 64.6 mm |
| 12 | X½ | 67 | 25 | 21.4 mm | 67.2 mm |
Buying a ring as a surprise?
Borrow a ring they wear on the right finger and measure it, or trace its inside edge on paper. If you can't, the average ring size guide explains the typical ranges and why sizing up is the safer guess. Many jewelers resize a plain band for free within a set period; eternity and tension-set rings usually can't be resized, so size those carefully.
Questions people ask
How does the ring size calculator work?
Enter the distance around your finger or the inside diameter of a ring that fits. The calculator converts it to inside circumference, then applies the published scales: US sizes step 0.8128 mm of diameter, UK letters step 1.25 mm of circumference (BS 6820), EU sizes equal the circumference in mm (ISO 8653), and Japanese and Indian sizes are matched from standard equivalency tables.
What if I land between two sizes?
Choose the larger size, especially for wide bands or if your knuckles are larger than the base of your finger. A slightly loose ring can be fitted with a sizing bead; one that will not pass the knuckle cannot be worn.
Is a finger measurement the same as a ring size?
It is the starting point. A string or paper strip measures the outside of your finger, which is what the ring must fit around. Measure two or three times at room temperature, later in the day, because fingers swell with heat and shrink in the cold.
Can I trust an online ring size calculator for an engagement ring?
It is accurate enough to order confidently, and the maths here is exact to the standards. For a high-value ring, confirm with a jeweler's metal sizer, and check the retailer's free-resize policy.