How to measure ring size at home
You do not need a ring sizer. A strip of paper or a piece of string, a ruler with millimetres, and four steps will get you an accurate size.
You can find your ring size at home with nothing more than a strip of paper or a piece of string and a ruler with millimetres. The key is to measure the circumference of the finger where the ring will sit, then convert that measurement to a size.
Measure at the end of the day when your fingers are at their largest, and take the reading two or three times. Fingers swell in heat and shrink in cold, so an average is more reliable than a single measurement.
- Wrap a paper strip around your finger. Cut a thin strip of paper or use a length of string and wrap it snugly around the base of the finger, below the knuckle where the ring will rest.
- Mark and measure. Mark where the strip overlaps, then lay it flat against a ruler and read the length in millimetres. That length is your inside circumference.
- Check it clears your knuckle. Slide the marked loop over your knuckle to confirm it passes with gentle resistance. The ring has to get over the knuckle but stay put once on.
- Convert the measurement to a size. Match your circumference in millimetres to the chart to read your US number, UK letter or EU size. If you land between two sizes, choose the larger one.
Prefer to print and measure? The printable ring sizer gives you circles to match an existing ring and a finger strip to wrap and read.
Circumference to ring size
Once you have your inside circumference in millimetres, read across to your size.
| US / Canada | UK / Australia | EU / ISO | Japan / China | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14.1 | 44.2 |
| 3.5 | G | 45 | 5 | 14.5 | 45.5 |
| 4 | H | 47 | 7 | 14.9 | 46.8 |
| 4.5 | I | 48 | 8 | 15.3 | 48 |
| 5 | J | 49 | 9 | 15.7 | 49.3 |
| 5.5 | K | 50 | 10 | 16.1 | 50.6 |
| 6 | L | 52 | 12 | 16.5 | 51.9 |
| 6.5 | M | 53 | 13 | 16.9 | 53.1 |
| 7 | N | 54 | 14 | 17.3 | 54.4 |
| 7.5 | O | 56 | 15 | 17.7 | 55.7 |
| 8 | P | 57 | 16 | 18.1 | 57 |
| 8.5 | Q | 58 | 17 | 18.5 | 58.3 |
| 9 | R | 59 | 18 | 19 | 59.5 |
| 9.5 | S | 61 | 19 | 19.4 | 60.8 |
| 10 | T | 62 | 20 | 19.8 | 62.1 |
| 10.5 | U | 63 | 22 | 20.2 | 63.4 |
| 11 | V | 64 | 23 | 20.6 | 64.6 |
| 11.5 | W | 66 | 24 | 21 | 65.9 |
| 12 | X | 67 | 25 | 21.4 | 67.2 |
| 12.5 | Y | 68 | 26 | 21.8 | 68.5 |
| 13 | Z | 69 | 27 | 22.2 | 69.7 |
Measuring questions
How do I measure ring size at home without a ring sizer?
Wrap a strip of paper or string around the base of your finger, mark the overlap, and measure the length in millimetres with a ruler. That circumference converts directly to a ring size using the chart.
What if I am between two ring sizes?
Choose the larger of the two. A ring that is slightly loose can be resized down or worn with a sizer insert, but a ring that is too tight will not go on.
Can I measure ring size with an existing ring?
Yes. Measure the inside diameter of a ring that already fits with a ruler in millimetres, then read that diameter on the chart. This is often more accurate than measuring the finger.
Last reviewed and updated on July 2, 2026. Conversion tables are checked against published international sizing standards.