Finding your ring size
Two ways to measure at home, what the size numbers mean, and when to size up rather than down.
Ring size is the inside circumference of the band in millimetres. A size 17 ring measures 17 mm across the inside; a size 54 measures 54 mm around it. Both numbering systems describe the same thing from different directions, which is why you will see both.
The most reliable method: measure a ring she already wears
Take a ring that fits the correct finger, lay it on a ruler, and measure the inside diameter across the widest point, in millimetres. That number is the diameter size. Multiply it by 3.14 for the circumference size.
| Inside diameter | Circumference | Common labels |
|---|---|---|
| 15.7 mm | 49 mm | 5 (US) |
| 16.5 mm | 52 mm | 6 (US) |
| 17.3 mm | 54 mm | 7 (US) |
| 18.1 mm | 57 mm | 8 (US) |
| 18.9 mm | 59 mm | 9 (US) |
Measure the ring, not the finger, whenever you can — it is the more accurate of the two, and it works when you are buying a surprise.
Measuring the finger instead
Wrap a strip of paper or a piece of non-stretch string around the base of the finger, snug but not tight. Mark where it overlaps, lay it flat, and measure the length in millimetres. That length is the circumference size.
Do it two or three times and take the largest reading. And do it at the end of the day: fingers are at their smallest in the morning and in cold weather, and a ring measured cold will be tight by evening.
When to go up a size
- Wide bands sit tighter than narrow ones at the same nominal size. For a band over about 6 mm wide, go up a quarter to a half size.
- Large knuckles. The ring has to pass the knuckle and then not spin at the base. Size to the knuckle and expect a slightly loose fit below it — a small adjustment can take up the difference.
- Heat. Fingers swell in summer and after exercise. If the ring is only just going on in February, it will not go on in August.
If you are between sizes, go up rather than down. A ring slightly too large can be made smaller easily; one that will not pass the knuckle cannot be worn at all.
Sizing a gift without asking
Borrow a ring she wears on the right finger and measure it as above. If you can only get a ring from a different finger, know that the middle finger usually runs about one size larger than the ring finger on the same hand.
If you are unsure, buy the size you think is closest — resizing is straightforward on most plain and partly-set bands.
What can and cannot be resized
Most plain bands and partly-set rings can be resized up or down a size or two. Full eternity bands set all the way round usually cannot, because there is no plain metal to cut and rejoin — for those, the size has to be right at purchase.
We resize and polish pieces bought here for as long as you own them. See caring for gold and silver for keeping the fit and finish right in between.