Check the scale first. Ring sizes are only about 0.8 mm apart in diameter, so a printer that shrinks the page by 3% will put you a full size off. Print at 100% and measure the bars at the bottom of the sheet before you use it.
Method 1: finger strip
- Cut out the strip along its solid outline.
- Wrap it around the base of your finger with the numbers facing out, so the numbered end overlaps the line marked START.
- Pull it snug, but loose enough to slide over the knuckle. The US size that lines up with START is your size. The top edge also gives the circumference in mm.
Method 2: an existing ring
Place a ring that fits the intended finger on the circles. The right size is the circle whose line just shows along the inside edge of the ring. If it falls between two sizes, choose the larger one.
Ring size chart
| US / Canada | Inside diameter | Circumference | EU / ISO |
|---|---|---|---|
| 3 | 14.1 mm | 44.2 mm | 44 |
| 3.5 | 14.5 mm | 45.5 mm | 45 |
| 4 | 14.9 mm | 46.8 mm | 47 |
| 4.5 | 15.3 mm | 48.0 mm | 48 |
| 5 | 15.7 mm | 49.3 mm | 49 |
| 5.5 | 16.1 mm | 50.6 mm | 51 |
| 6 | 16.5 mm | 51.9 mm | 52 |
| 6.5 | 16.9 mm | 53.1 mm | 53 |
| 7 | 17.3 mm | 54.4 mm | 54 |
| 7.5 | 17.7 mm | 55.7 mm | 56 |
| 8 | 18.1 mm | 57.0 mm | 57 |
| 8.5 | 18.5 mm | 58.2 mm | 58 |
| 9 | 18.9 mm | 59.5 mm | 60 |
| 9.5 | 19.4 mm | 60.8 mm | 61 |
| 10 | 19.8 mm | 62.1 mm | 62 |
| 10.5 | 20.2 mm | 63.3 mm | 63 |
| 11 | 20.6 mm | 64.6 mm | 65 |
| 11.5 | 21.0 mm | 65.9 mm | 66 |
| 12 | 21.4 mm | 67.2 mm | 67 |
| 12.5 | 21.8 mm | 68.5 mm | 68 |
| 13 | 22.2 mm | 69.7 mm | 70 |
EU/ISO sizes are the inside circumference in millimetres. US sizes use the standard formula: inside diameter = 11.63 mm + 0.8128 mm × size. Different jewellers' charts can differ by a quarter size, so for an expensive ring, confirm with the jeweller.
Tips for an accurate ring size
- Measure at the end of the day, when fingers are largest, and not when you are cold.
- Measure 3–4 times and use the most common result.
- Wide bands (6 mm or more) fit tighter, so go up half a size.
- If your knuckle is much wider than the base of your finger, choose a size that slides over the knuckle.
Frequently asked questions
Is a printable ring sizer accurate?
It can be accurate to within half a size if the sheet is printed at 100% and you check the scale bars. The ring-circle method, using a ring that already fits, is usually the most reliable.
What ring size is average?
As a rough guide, many women wear US 6 to 7 and many men wear US 9 to 10, but individual fingers vary a lot. Always measure.
How do I convert a US ring size to EU?
Use the chart above. EU size is the inside circumference in mm, so US 7 (17.3 mm diameter) is about EU 54.
Last reviewed 2026-10-07.