US ring size 5.5 in UK, Europe and India
US ring size 5.5 is UK size K½, European (ISO) size 50.6 and Indian/Japanese size 10. That is an inside diameter of 16.1 mm and an inside circumference of 50.58 mm.
How to check this is your size
The surest way is to measure a ring that already fits the right finger. Lay it flat and measure straight across the inside of the band. If it reads about 16.1 mm, you are a US 5.5.
If you have no ring to hand, wrap a strip of paper around the base of the finger, mark where it overlaps, and measure the length. About 50.58 mm means US 5.5. Measure at the end of the day, when fingers are at their largest — a ring sized on a cold morning will feel tight by evening.
Full conversion chart
| US | UK / AU | Europe | India / Japan | Diameter | Circumference |
|---|---|---|---|---|---|
| 3 | F | 44.1 | 4 | 14.05 mm | 44.14 mm |
| 3.25 | F½ | 44.8 | — | 14.25 mm | 44.77 mm |
| 3.5 | G | 45.4 | 5 | 14.45 mm | 45.4 mm |
| 3.75 | G½ | 46 | — | 14.65 mm | 46.02 mm |
| 4 | H | 46.7 | 6 | 14.86 mm | 46.68 mm |
| 4.25 | H½ | 47.3 | — | 15.06 mm | 47.31 mm |
| 4.5 | I | 48 | 7 | 15.27 mm | 47.97 mm |
| 4.75 | J | 48.6 | 8 | 15.47 mm | 48.6 mm |
| 5 | J½ | 49.3 | 9 | 15.7 mm | 49.32 mm |
| 5.25 | K | 50 | — | 15.9 mm | 49.95 mm |
| 5.5 | K½ | 50.6 | 10 | 16.1 mm | 50.58 mm |
| 5.75 | L | 51.2 | — | 16.3 mm | 51.21 mm |
| 6 | L½ | 51.9 | 11 | 16.51 mm | 51.87 mm |
| 6.25 | M | 52.5 | — | 16.71 mm | 52.5 mm |
| 6.5 | M½ | 53.2 | 12 | 16.92 mm | 53.16 mm |
| 6.75 | N | 53.8 | 13 | 17.13 mm | 53.82 mm |
| 7 | N½ | 54.5 | 14 | 17.35 mm | 54.51 mm |
| 7.25 | O | 55.1 | — | 17.55 mm | 55.13 mm |
| 7.5 | O½ | 55.8 | 15 | 17.75 mm | 55.76 mm |
| 7.75 | P | 56.5 | — | 17.97 mm | 56.45 mm |
| 8 | P½ | 57.1 | 16 | 18.19 mm | 57.15 mm |
| 8.25 | Q | 57.8 | — | 18.39 mm | 57.77 mm |
| 8.5 | Q½ | 58.2 | 17 | 18.53 mm | 58.21 mm |
| 8.75 | R | 59.1 | — | 18.8 mm | 59.06 mm |
| 9 | R½ | 59.5 | 18 | 18.95 mm | 59.53 mm |
| 9.25 | S | 60.4 | — | 19.22 mm | 60.38 mm |
| 9.5 | S½ | 61 | 19 | 19.41 mm | 60.98 mm |
| 9.75 | T | 61.6 | — | 19.62 mm | 61.64 mm |
| 10 | T½ | 62.3 | 20 | 19.84 mm | 62.33 mm |
| 10.25 | U | 62.9 | — | 20.02 mm | 62.89 mm |
| 10.5 | U½ | 63.5 | 22 | 20.2 mm | 63.46 mm |
| 10.75 | V | 64.2 | — | 20.44 mm | 64.21 mm |
| 11 | V½ | 65 | 23 | 20.68 mm | 64.97 mm |
| 11.5 | W½ | 66.2 | 24 | 21.08 mm | 66.22 mm |
| 12 | X½ | 67.5 | 25 | 21.49 mm | 67.51 mm |
| 12.5 | Y½ | 68.8 | 26 | 21.89 mm | 68.77 mm |
| 13 | Z½ | 70.2 | 27 | 22.33 mm | 70.15 mm |
A note on wide bands
A band wider than about 6 mm sits against more of your finger and feels tighter at the same measurement. Most jewellers suggest going up a quarter to a half size, so a US 5.5 in a narrow band is often a 6 in a wide one.
Measure it yourself, right now
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