Ring Size Converter
Convert ring sizes between US/Canada, UK/Australia, EU, Japan, and physical measurements (diameter and circumference in mm). Find your ring size across international standards.
How to Measure Your Ring Size at Home
You can determine your ring size at home using simple materials. The two most common methods are the string method and the paper strip method. For best results, measure at the end of the day when fingers are slightly larger, and measure multiple times for consistency.
String Method
- Wrap a piece of string or dental floss around the base of your finger
- Mark where the string overlaps
- Lay the string flat and measure the length in millimeters
- This measurement is your circumference — use the chart below to find your size
Paper Strip Method
- Cut a thin strip of paper (about 10mm wide)
- Wrap it around your finger snugly but not tight
- Mark where the paper overlaps with a pen
- Measure the distance from the end to the mark in millimeters
Ring Size Conversion Formula
US Size = (Circumference_mm - 36.5) / 2.55
Circumference = Diameter x pi (3.14159)
UK Size = Letter corresponding to US size (A=0.5, B=1, ...)
EU Size = Circumference in mm (approximate)
Complete Ring Size Conversion Chart
| US/Canada | UK/AU | EU | Japan | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|---|
| 3 | F | 44 | 4 | 14.1 | 44.2 |
| 3.5 | G | 45.5 | 5 | 14.3 | 44.8 |
| 4 | H | 46.8 | 7 | 14.9 | 46.8 |
| 4.5 | I | 48 | 8 | 15.3 | 48 |
| 5 | J | 49.3 | 9 | 15.7 | 49.3 |
| 5.5 | K | 50.6 | 10 | 16.1 | 50.6 |
| 6 | L | 51.9 | 12 | 16.5 | 51.9 |
| 6.5 | M | 53.1 | 13 | 16.9 | 53.1 |
| 7 | N | 54.4 | 14 | 17.3 | 54.4 |
| 7.5 | O | 55.7 | 15 | 17.7 | 55.7 |
| 8 | P | 57 | 16 | 18.1 | 57 |
| 8.5 | Q | 58.3 | 17 | 18.5 | 58.3 |
| 9 | R | 59.5 | 18 | 18.9 | 59.5 |
| 9.5 | S | 60.8 | 19 | 19.4 | 60.8 |
| 10 | T | 62.1 | 20 | 19.8 | 62.1 |
| 10.5 | U | 63.4 | 22 | 20.2 | 63.4 |
| 11 | V | 64.6 | 23 | 20.6 | 64.6 |
| 11.5 | W | 65.9 | 24 | 21 | 65.9 |
| 12 | X | 67.2 | 25 | 21.4 | 67.2 |
| 12.5 | Y | 68.5 | 26 | 21.8 | 68.5 |
| 13 | Z | 69.7 | 27 | 22.2 | 69.7 |
Ring Resizing Tips
Most rings can be resized up or down by 1-2 sizes. Sizing up is generally easier and less expensive than sizing down. Rings with stones set all around (eternity bands) or those made from certain materials (tungsten, titanium, ceramic) cannot be resized. When in doubt, order slightly larger — a ring that is too big can be made smaller with sizing beads or a ring guard, while a too-small ring may need to be cut and resoldered.
Frequently Asked Questions
What is the most common ring size?
The most common ring size for women is US 6-7 (UK L-N), and for men is US 9-10 (UK R-T). However, ring size varies significantly between individuals.
Do ring sizes change with temperature?
Yes. Fingers swell in heat and shrink in cold. A ring that fits perfectly in summer may be loose in winter. For the most accurate measurement, measure at room temperature at the end of the day.
Is my ring size the same on all fingers?
No. Each finger has a different size, and your dominant hand is typically slightly larger. Always measure the specific finger you plan to wear the ring on.
How do I convert UK letter sizes to numbers?
UK sizes use letters A through Z. They correspond roughly to US sizes starting at A = 0.5 and increasing by 0.5 for each letter. Use the conversion chart above for exact equivalents.
What if my measurement falls between two sizes?
If your measurement falls between two sizes, choose the larger size for comfort. A slightly loose ring is more comfortable than a tight one, and can be adjusted with sizing inserts if needed.
Does ring width affect sizing?
Yes. Wider bands (over 6mm) fit more snugly than narrow bands. If choosing a wide band, consider going up half a size from your standard measurement for a comfortable fit.