Ring Size Converter → Ring Size Chart
Ring Size Chart
Every ring size, side by side — US, UK/Australia, Europe, and Japan, with the exact diameter and circumference in millimeters. Measure right on your screen below, or type a measurement into the converter.
On-screen ring sizer (actual size)
No ruler? Calibrate to a bank card, then lay a ring over the circle to read your size directly.
Step 1 · Calibrate your screen
Hold a standard bank card (or any credit/ID card) flat against the screen and drag the slider until the outline below exactly matches its width. Every screen is different — this makes the ring circles true-to-life.
Step 2 · Match your ring
Place a ring that fits over the circle. The right size is where the circle sits just inside the ring's inner edge. Use the arrows to change size.
Full ring size conversion chart
| US / CA | UK / AU | Europe | Japan | Diameter (mm) | Circumference (mm) | Common |
|---|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14.1 | 44.2 | |
| 3.5 | G | 45½ | 5 | 14.5 | 45.5 | |
| 4 | H½ | 47 | 7 | 14.9 | 46.8 | |
| 4.5 | I½ | 48 | 8 | 15.3 | 48.0 | |
| 5 | J½ | 49 | 9 | 15.7 | 49.3 | ♀ women |
| 5.5 | K½ | 50½ | 10 | 16.1 | 50.6 | ♀ women |
| 6 | L½ | 52 | 11 | 16.5 | 51.9 | ♀ women |
| 6.5 | M½ | 53 | 12 | 16.9 | 53.1 | ♀ women |
| 7 | N½ | 54 | 13 | 17.3 | 54.4 | ♀ women |
| 7.5 | O½ | 55½ | 14 | 17.7 | 55.7 | ♀ women |
| 8 | P½ | 57 | 16 | 18.1 | 57.0 | ♂ men |
| 8.5 | Q½ | 58 | 17 | 18.5 | 58.3 | ♂ men |
| 9 | R½ | 59½ | 18 | 19.0 | 59.5 | ♂ men |
| 9.5 | S½ | 61 | 19 | 19.4 | 60.8 | ♂ men |
| 10 | T½ | 62 | 20 | 19.8 | 62.1 | ♂ men |
| 10.5 | U½ | 63½ | 22 | 20.2 | 63.5 | ♂ men |
| 11 | V½ | 65 | 23 | 20.6 | 64.6 | ♂ men |
| 11.5 | W½ | 66 | 24 | 21.0 | 65.9 | ♂ men |
| 12 | Y | 67½ | 25 | 21.4 | 67.2 | ♂ men |
| 12.5 | Z | 68½ | 26 | 21.8 | 68.4 | |
| 13 | Z+1 | 70 | 27 | 22.2 | 69.7 |
Industry-standard approximations; individual manufacturers vary slightly. Between sizes? Round up — wide bands fit more snugly.
Frequently asked questions
What is the most common ring size?
Most women fall between US size 5 and 7 (UK J½–N½), and most men between US 9 and 11 (UK R½–V½). These are averages only — finger size varies a lot, so measure rather than guess, especially for a surprise or a fixed-size band.
How do I read a ring size chart?
Find your measurement — either the inside diameter/circumference of a ring that fits, or a size you already know in one country — then read across the row for the equivalent in every other standard. US/Canada is numeric, UK/Australia is letters, Europe (ISO) is the circumference in millimeters, and Japan uses its own numbers.
How much is one ring size in mm?
One full US size is about 0.4 mm of inside diameter, or roughly 1.3 mm of circumference. Because the steps are small, a measurement error of even 1 mm can put you off by a full size — measure carefully.
Is the on-screen ring sizer accurate?
Only after you calibrate it. Screens differ in pixel density, so first match a real bank card to the outline; that sets the true scale. Then the ring circles are shown at actual size. For an engagement ring, still confirm with a jeweler.