Everything you need to know about engagement ring sizing — including how to find her size secretly and what to do if you get it slightly wrong.
Getting the ring size right for an engagement ring matters more than for any other ring. These rings are emotionally significant, often expensive, and may have complex settings that make resizing difficult. This guide gives you every strategy to get it right.
This is the most reliable method. Take a ring she currently wears on her ring finger (left hand in the US/UK; right hand in many European countries). Take it to any jeweller — they will measure it in under a minute for free. Alternatively, measure the inside diameter yourself with a ruler in mm.
Her best friend, sister, or mother may know her ring size from previous shopping trips. This is often the second most reliable route.
Press her ring into a bar of soap or a piece of putty while she sleeps. The impression left gives you the inside diameter — measure it and use our chart.
Carefully wrap a thin piece of string around her ring finger while she sleeps. Mark and measure it. This gives circumference in mm.
Many couples today discuss ring shopping before the formal proposal. Asking directly removes all guesswork, and many people prefer it. The surprise can still be in the timing and style of the proposal.
If you cannot determine her size by any means:
Most engagement rings can be resized, but there are important limitations:
Plain solitaire settings in gold, white gold, or platinum. Most simple band designs. Typically up or down 1–2 sizes without issue.
Rings with stones set in the band (channel set, pavé), or rings with intricate engraving. Resizing may affect the stone setting or pattern.
Full eternity rings (stones all the way around), tension-set rings, tungsten, titanium, and ceramic rings. Get these sized precisely before purchase.
| US / Canada | UK / IRE | EU | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|
| 4 | H | 46.5 | 14.9 | 46.8 |
| 4.5 | I | 48 | 15.3 | 48.0 |
| 5 | J | 49 | 15.7 | 49.3 |
| 5.5 | K | 50.5 | 16.1 | 50.6 |
| 6 | L | 51.5 | 16.5 | 51.9 |
| 6.5 | M | 53 | 16.9 | 53.2 |
| 7 | N | 54 | 17.3 | 54.4 |
| 7.5 | O | 55.5 | 17.7 | 55.7 |
| 8 | P | 57 | 18.2 | 57.2 |