In the UK, finger sizes are measured in letters and ½ sizes. It is also possible to have ¼ sizes as well.
An average UK ladies finger size is N. An average UK men's finger size is S.
95% of ladies finger sizes fall within the range of J to Q.
If you already know your required finger size/s, then you don't need to read on any further.
If you don't already know your required finger size or if you are making a secret purchase of a ring, then the best way to ascertain her finger size is to measure the INTERNAL diameter (left to right measurement) of one of her existing rings and then equate this to a UK finger size using the chart below. For example, if you measure the internal diameter of her ring to be 16mm, then you need a size K ½. Do note that there are fractions of difference between the various sizes so be as accurate as possible when taking your measurements. Note also that finger sizes can increase or decrease fractionally, depending upon the ambient temperature.
| SIZE | DIAMETER (MM) |
| E | 13.61 |
| E ½ | 13.83 |
| F | 14.05 |
| F ½ | 14.15 |
| G | 14.36 |
| G ½ | 14.56 |
| H | 14.65 |
| H ½ | 14.86 |
| I | 15.04 |
| I ½ | 15.27 |
| J | 15.40 |
| J ½ | 15.70 |
| K | 15.80 |
| K ½ | 16.00 |
| L | 16.10 |
| L ½ | 16.41 |
| M | 16.51 |
| M ½ | 16.71 |
| N | 16.92 |
| N ½ | 17.13 |
| O | 17.35 |
| O ½ | 17.45 |
| P | 17.75 |
| P ½ | 17.97 |
| Q | 18.19 |
| Q ½ | 18.35 |
| R | 18.61 |
| R ½ | 18.80 |
| S | 19.10 |
| S ½ | 19.31 |
| T | 19.51 |
| T ½ | 19.84 |
| U | 20.02 |
| U ½ | 20.20 |
| V | 20.32 |
| V ½ | 20.68 |
| W | 20.76 |
| W ½ | 20.94 |
| X | 21.18 |
| X ½ | 21.30 |
| Y | 21.49 |
| Y ½ | 21.69 |
| Z | 21.89 |
Getting the size correct first time is particularly important when buying full eternity rings, as once these rings have been produced, they cannot be resized. On all other rings, DeJoria offers a free re-sizing service as part of our Lifetime Care Programme.