Ring size
UK sizes run as letters. What the letter actually refers to is the inner circumference of the band in millimetres, which is the only measurement that matters and the one you can check at home with a strip of paper.
Last updated 12 August 2026
Measuring at home
- Cut a strip of paper about 6 mm wide and 100 mm long. Paper, not string — string stretches.
- Wrap it round the base of the finger, snug but not tight, and mark where it overlaps.
- Lay it flat and measure to the mark in millimetres. That is your inner circumference.
- Find it in the table below and take the nearest letter. Between two sizes, go up.
Two things that ruin an otherwise careful measurement:
- Temperature. Fingers are measurably smaller when cold. Measure at the end of the day, at room temperature, not first thing on a winter morning.
- The knuckle. The ring has to pass over it. If your knuckle is noticeably larger than the base of the finger, measure both and choose something between the two — closer to the knuckle measurement for a ring you will take on and off often.
Measuring a ring you already own
Measure the inside diameter across the widest point in millimetres and find it in the second column. Do this with a ring that fits the same finger on the same hand — most people’s hands differ by about half a size.
UK letter codes
| UK | Inner circumference | Inner diameter | US approx. | EU approx. |
|---|---|---|---|---|
| H | 47.4 mm | 15.1 mm | 3¾ | 48 |
| I | 48.0 mm | 15.3 mm | 4¼ | 48½ |
| J | 48.7 mm | 15.5 mm | 4½ | 49 |
| K | 49.9 mm | 15.9 mm | 5 | 50 |
| L | 51.2 mm | 16.3 mm | 5½ | 51 |
| M | 52.5 mm | 16.7 mm | 6 | 52½ |
| N | 53.8 mm | 17.1 mm | 6½ | 54 |
| O | 55.1 mm | 17.5 mm | 7 | 55 |
| P | 56.3 mm | 17.9 mm | 7½ | 56 |
| Q | 57.6 mm | 18.3 mm | 8¼ | 57½ |
| R | 58.9 mm | 18.8 mm | 8¾ | 59 |
| S | 60.2 mm | 19.2 mm | 9¼ | 60 |
| T | 61.4 mm | 19.6 mm | 9¾ | 61½ |
US and EU figures are approximate conversions and are given for orientation only. Order by the UK letter or, better, by the millimetre measurement.
Band width changes the fit
A wide band sits tighter than a narrow one of the same nominal size, because it grips more of the finger. On a band over about 6 mm wide, go up half a size. The band widths in this shop are given on each product page.
Resizing
Plain bands and simple settings can usually be resized by a size or two either way. It is chargeable and quoted case by case — see terms, clause 10.
What we will not resize:
- Flush-set bands, where moving the metal distorts the seat the stone sits in.
- Anything with a fracture-filled stone still in it, because resizing needs heat and heat drives filler out.
- Rings with stones set all the way round.
If you are unsure of the size, it is far easier to use the 14 day right to change your mind and exchange it than to have a ring altered. Stock rings come back to us unaltered and go out again in the right size.
If you are still not sure
Call +44 7196509962 or email support@ishtarjewellery.shop and we will talk it through. For a gift, where you cannot measure the finger, tell us the height and build of the person and whether they wear rings already — it is a rough guide, but it is better than a guess, and the 14 day right covers the rest.