The circle shows the inside of the ring. It is real size after you set up the screen in Measure on screen.
Ring size chart
First, set the real size with a bank card
Hold any bank card, ID card or loyalty card against the screen, on the blue card. Move the slider until both are exactly the same width.
This is the same setting as the Online Ruler. You set it once for each screen.
Put a ring that fits you flat on the circle. Make the circle bigger or smaller until its edge lines up with the inside edge of the ring.
Print at 100% (Actual size), not “Fit to page”. Then check the 50 mm line on the sheet with a ruler.
Making the PDF…
About the ring size chart
This page has three ways to find a ring size:
- Size chart — pick a size you know (US, UK, Europe, Japan, or the inside of a ring in mm) and see it in every other system, with the full chart below.
- Measure on screen — put a ring that fits you on your screen and make the circle match it. The screen is first set to real size with a bank card — the same setting as our Online Ruler, so you only do it once.
- Printable sizer — a one-page PDF with ring circles, a paper strip to wrap around your finger, and a 50 mm check line so you can be sure it printed at the right size.
Every size comes from the inside of the ring: its diameter or its circumference, in millimetres.
Features
- 4 size systems — US and Canada, UK / Ireland / Australia / NZ, Europe (ISO) and Japan
- Millimetres and inches — the inside diameter and circumference of every size
- On-screen sizer — quarter sizes from US 1 to 16, real size after a 20-second card setup
- Shared screen setup — one setup for this page and the Online Ruler
- Printable ring sizer — circles plus a finger strip, with a 50 mm check line
- 4 styles and 3 size ranges — Classic, Minimal, Rose gold or Bold; US 3–13, 1–8 or 8–16
- US Letter or A4 — and Print or Download in one click
Ring size chart (US, UK, EU, Japan)
| US / Canada | UK / Australia | Europe | Japan | Inside diameter | Inside circumference |
|---|---|---|---|---|---|
| 3 | F½ | 44 | 4 | 14.1 mm (0.55 in) | 44.2 mm |
| 3½ | G½ | 45 | 5 | 14.5 mm (0.57 in) | 45.5 mm |
| 4 | H½ | 47 | 7 | 14.9 mm (0.59 in) | 46.8 mm |
| 4½ | I½ | 48 | 8 | 15.3 mm (0.60 in) | 48.0 mm |
| 5 | J½ | 49 | 9 | 15.7 mm (0.62 in) | 49.3 mm |
| 5½ | K½ | 51 | 10 | 16.1 mm (0.63 in) | 50.6 mm |
| 6 | L½ | 52 | 12 | 16.5 mm (0.65 in) | 51.9 mm |
| 6½ | M½ | 53 | 13 | 16.9 mm (0.67 in) | 53.1 mm |
| 7 | N½ | 54 | 14 | 17.3 mm (0.68 in) | 54.4 mm |
| 7½ | O½ | 56 | 15 | 17.7 mm (0.70 in) | 55.7 mm |
| 8 | P½ | 57 | 16 | 18.1 mm (0.71 in) | 57.0 mm |
| 8½ | Q½ | 58 | 18 | 18.5 mm (0.73 in) | 58.2 mm |
| 9 | R½ | 60 | 19 | 18.9 mm (0.75 in) | 59.5 mm |
| 9½ | S½ | 61 | 20 | 19.4 mm (0.76 in) | 60.8 mm |
| 10 | T½ | 62 | 21 | 19.8 mm (0.78 in) | 62.1 mm |
| 10½ | U½ | 63 | 22 | 20.2 mm (0.79 in) | 63.3 mm |
| 11 | V½ | 65 | 24 | 20.6 mm (0.81 in) | 64.6 mm |
| 11½ | W½ | 66 | 25 | 21.0 mm (0.83 in) | 65.9 mm |
| 12 | X½ | 67 | 26 | 21.4 mm (0.84 in) | 67.2 mm |
| 12½ | Z | 68 | 27 | 21.8 mm (0.86 in) | 68.5 mm |
| 13 | Z+1 | 70 | 29 | 22.2 mm (0.87 in) | 69.7 mm |
The most common sizes are about US 6–7 for women and US 9–10 for men.
How the sizes are made
Each system is a simple formula on the inside of the ring. The chart above and the tool use the same formulas, then round to the nearest size in each system.
| System | Rule |
|---|---|
| US and Canada | inside diameter = 11.63 mm + 0.8128 mm × size (0.032 in per size); quarter sizes exist |
| UK, Ireland, Australia, NZ | inside circumference = 37.5 mm + 1.25 mm per letter, from A; half sizes; after Z come Z+1, Z+2 … |
| Europe (ISO 8653) | the size is the inside circumference in mm |
| Japan | inside diameter = 13 mm for size 1, plus ⅓ mm per size |
So US 7 has an inside diameter of 11.63 + 0.8128 × 7 = 17.3 mm and a circumference of π × 17.32 = 54.4 mm — Europe 54, UK N½, Japan 14.
Japanese sizes by the same rule:
| Japan | Inside diameter | Circumference | Closest US |
|---|---|---|---|
| 5 | 14.3 mm | 45.0 mm | 3¼ |
| 7 | 15.0 mm | 47.1 mm | 4¼ |
| 9 | 15.7 mm | 49.2 mm | 5 |
| 11 | 16.3 mm | 51.3 mm | 5¾ |
| 13 | 17.0 mm | 53.4 mm | 6½ |
| 15 | 17.7 mm | 55.5 mm | 7½ |
| 17 | 18.3 mm | 57.6 mm | 8¼ |
| 19 | 19.0 mm | 59.7 mm | 9 |
| 21 | 19.7 mm | 61.8 mm | 10 |
How to use the printable ring sizer
- Open Printable sizer and download or print the PDF.
- Print at 100% ("Actual size"). Do not use "Fit to page" — it makes everything smaller.
- Check the 50 mm line with a ruler. If it is not exactly 50 mm, the sizes are wrong: print again at 100%.
- Circles: put a ring that fits you on the circles. Your size is the circle whose line you can just see inside the ring.
- Strip: cut it out, wrap it around the base of your finger with the numbers outside, and read the US size on top — or the mm below, which is your European size.
How to measure a ring on the screen
- Open Measure on screen. The first time, hold a bank card against the blue card and move the slider until both are the same width, then press It fits — save.
- Put a ring that fits you flat on the screen, over the circle.
- Use −, + or the slider until the edge of the circle lines up with the inside edge of the ring.
- Read the size below the circle.
The setting is saved for this screen. If you zoom the page or move to another monitor, set it up again. Do not press hard on the screen.
Frequently asked questions
How do I find my ring size at home?
Measure a ring that already fits you: put it on the screen sizer, or on the printed circles. Or wrap the printed paper strip around your finger. A string and a ruler work too: wrap it around your finger, mark it, and measure the length in mm — that is your European size.
What is US 7 in mm?
A US 7 has an inside diameter of 17.3 mm and an inside circumference of 54.4 mm. That is about Europe 54, UK N½ and Japan 14.
How do I convert a UK ring size to US?
Find the UK letter in the chart. UK N½ is US 7, UK L½ is US 6 and UK P½ is US 8. Each full UK letter is 1.25 mm around; each full US size is about 2.55 mm around, so one US size is about two UK letters.
Is the printable ring sizer accurate?
Yes, if it prints at 100%. That is why the sheet has a 50 mm check line. A printer set to "Fit to page" shrinks the page by a few percent, and the sizes are then too small.
Should I size up for a wide ring?
Yes. A band wider than about 6 mm fits tighter, so many jewelers suggest half a size bigger. Also measure when your fingers are warm, at the end of the day.
Why is the on-screen circle the wrong size?
A browser does not know how big your screen's pixels are. Set it up once with a bank card (85.60 mm wide — the same size everywhere). If you zoom the page, set it up again.
Related tools
- Online Ruler — a real-size ruler on your screen, with the same card setup
- Shoe Size Converter — US, UK, EU and cm shoe sizes
- CM to Inches — mm and cm into inches
- Unit Converter — every length unit
How to use it
- Size chart: choose what you know in I know my size in, then pick the Size — or type the inside diameter or circumference in mm. Read every other size in the result, and see your row in the Ring size chart
- Measure on screen: set up the screen with a bank card the first time, then put your ring on the circle and change the size with −, + or the slider until they match
- Printable sizer: choose a Style, the Paper and the Sizes, then press Print or Download PDF. Print at 100% and check the 50 mm line
