Check the size
Updated November 2026
Relax: you don't need her exact size. You need to be within about half a size, buying a resizable ring, from a seller who resizes free. Hit those three and the sizing problem dissolves. Here's how to get there without one suspicious question.
The check: get within half a size using the moves below, err half a size large (sizing down is easier than up), and confirm the ring style is resizable and the resize policy is in writing before you pay.
The covert options, ranked
- Borrow and trace. A ring she already wears (left or right ring finger is close enough) — trace the inside circle on paper or press it into a bar of soap, measure the diameter, return it before it's missed. Gold standard.
- Recruit an ally. Her sister or best friend can land the exact number in one casual mall try-on. Choose someone who can keep a secret longer than a group chat.
- Photo with a coin. If borrowing is too risky, a photo of a ring next to a quarter gives a jeweler enough for a solid estimate.
- The average, as a last resort. Most women's rings run 6–6.5. Buy a 6.5 resizable and let the free resize do the rest.
The chart
| US size | Diameter | US size | Diameter |
|---|---|---|---|
| 5 | 15.7 mm | 7 | 17.3 mm |
| 5.5 | 16.1 mm | 8 | 18.1 mm |
| 6 | 16.5 mm | 9 | 19.0 mm |
| 6.5 | 16.9 mm | 10 | 19.8 mm |
Resize reality
| Job | Cost | Verdict |
|---|---|---|
| Down up to 2 sizes | $50–$100 | Routine |
| Up up to 2 sizes | $75–$150 | Routine (more in platinum/18k) |
| Pavé / detailed bands | $150–$350 | Stones get reset |
| Full eternity, tension, some channel-set | — | Often impossible — exchange, don't resize |
Which is why the setting check says: guessing at the size? Nothing unresizable. And why the seller check makes a written free-first-resize policy a dealbreaker — it converts your size guess from a gamble into a formality.