1Measure a ring you already own
Choose a ring that fits the intended finger. Lay it flat and measure the inside diameter in millimetres, edge to edge across the centre. Match that figure to the chart below.
2Measure your finger
Wrap a strip of paper or a piece of string around the base of the finger. Mark where it overlaps, lay it flat against a ruler, and read the length in millimetres. That is your circumference.
Before you measure
- Measure at the end of the day, when fingers are at their largest.
- Avoid measuring when hands are cold — fingers can be up to half a size smaller.
- The ring must pass over the knuckle. If your knuckle is noticeably larger, size to the knuckle.
- Wide or heavy bands sit tighter. Consider going up a quarter to half size.
| US size | Inside diameter | Inside circumference |
|---|
| US 3 | 14.07 mm | 44.2 mm |
| US 3.5 | 14.45 mm | 45.4 mm |
| US 4 | 14.86 mm | 46.7 mm |
| US 4.5 | 15.27 mm | 48.0 mm |
| US 5 | 15.70 mm | 49.3 mm |
| US 5.5 | 16.10 mm | 50.6 mm |
| US 6 | 16.51 mm | 51.9 mm |
| US 6.5 | 16.92 mm | 53.2 mm |
| US 7 | 17.35 mm | 54.5 mm |
| US 7.5 | 17.75 mm | 55.8 mm |
| US 8 | 18.19 mm | 57.2 mm |
| US 8.5 | 18.53 mm | 58.2 mm |
| US 9 | 18.95 mm | 59.5 mm |
| US 9.5 | 19.41 mm | 61.0 mm |
| US 10 | 19.84 mm | 62.3 mm |
| US 10.5 | 20.20 mm | 63.5 mm |
| US 11 | 20.68 mm | 65.0 mm |
| US 11.5 | 21.08 mm | 66.2 mm |
| US 12 | 21.49 mm | 67.5 mm |
| US 12.5 | 21.89 mm | 68.8 mm |
| US 13 | 22.33 mm | 70.2 mm |
Quarter sizes such as US 6.25 fall midway between the rows above. If you know your UK or EU size, match it by circumference rather than converting the number.
Before you resize
Rings that have been altered or resized by another jeweller are not eligible for return. Full terms are in our Return & Refund Policy.
If you are between sizes or unsure, contact us before ordering and we will help you choose.
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