Ring Sizing and Resizing: What Can and Cannot Be Resized
Tension settings cannot be resized. Full eternity bands usually cannot. Most people do not know this before they buy. Here is everything you need to know before committing to a ring.
Updated April 2026
Ring Size Basics
Ring sizes vary by country. The US uses a numeric scale with half-sizes (5, 5.5, 6, 6.5, etc.). The UK uses an alphabetic scale (J, K, L, M, etc.). Continental Europe uses a numeric millimetre-based scale. Australia uses a similar alphabetic scale to the UK.
| US Size | UK Size | EU Size | Diameter (mm) |
|---|---|---|---|
| 5 | J/K | 49 | 15.7 |
| 5.5 | K/L | 50 | 15.9 |
| 6 | L/M | 51 | 16.5 |
| 6.5 | M/N | 53 | 16.9 |
| 7 | N/O | 55 | 17.3 |
| 7.5 | O/P | 56 | 17.7 |
| 8 | P/Q | 57 | 18.1 |
| 8.5 | Q/R | 58 | 18.5 |
| 9 | R/S | 59 | 18.9 |
| 10 | T/U | 61 | 19.8 |
How to Measure at Home
The most reliable home measurement method: cut a strip of paper about 5mm wide and 10cm long. Wrap it snugly around the base of the ring finger. Mark where the paper overlaps. Measure the length in millimetres. Divide by 3.14 to get the diameter in millimetres, then use a conversion table.
Measurement tips
- +Measure at the end of the day when fingers are slightly larger from swelling.
- +Measure when hands are warm. Fingers shrink in cold weather.
- +If between two sizes, go with the larger.
- +The ring should slide over the knuckle with slight resistance and fit snugly at the base without spinning.
- +Wider bands (6mm+) typically need to be half a size larger because they apply more friction to the finger.
What Can and Cannot Be Resized
| Setting type | Resizable? | Notes |
|---|---|---|
| Plain metal band | Yes (2+ sizes) | Straightforward; standard resizing |
| Prong solitaire | Yes (1-2 sizes) | Prongs checked after; common resizing |
| Halo setting | Yes (1 size typically) | Halo limits resize range |
| Pavé band | Limited (0.5-1 size) | Stone placement disrupted with larger resize |
| Channel-set band | Limited (1 size) | Channel walls may crack with larger resize |
| Half-eternity band | Yes (1-1.5 sizes) | Resize at plain back section |
| Full eternity band | Usually not | Stones 360 degrees; no plain section to resize |
| Tension setting | Usually not | Tension force changes; stone may loosen |
| Stackable bands | Yes (individual) | Each band resized separately |
| Titanium/tungsten rings | No | Metal cannot be resized; must buy new size |
| Vintage/antique rings | Depends | Complex metalwork; assess before attempting |
Finger Size Changes Over Time
Finger size is not fixed. Weight fluctuation, pregnancy, age-related changes, and temperature all affect ring fit. Pregnancy typically causes finger swelling that can make rings unwearable for the third trimester and a period after birth. Some people gain or lose sufficient weight to go up or down a full ring size.
For temporary size changes, ring size beads (small metal beads soldered to the inner shank) or a ring guard (a thin band worn between the ring and the finger) can compensate for a ring that is temporarily loose. These cost $20-$50 at most jewellers.
For permanent size changes of more than 2 sizes, resetting the stone in a new shank is often more cost-effective and structurally better than attempting a large resize.