Visiting a local jewellery store and having your finger size measured will give you a fairly accurate idea but there is sometimes one or two finger sizes variance between different stores due to slight differences in measuring equipment and methods. The width of the ring and how curved the inside surface is will also affect size accuracy. A wider ring requires a bigger finger size than a narrower ring. A comfort fit ring with a curved inside surface goes on easier so can be half a size smaller than a flatter profiled ring.
This international conversion guide will help if you are not from Ireland or the UK. If you can’t visit a jewellery store, a simple way can be to bend a strip of paper around the finger and mark wear it meets. Measure against a ruler and use the circumference below to work out your size. If you have larger knuckles, measure around your knuckle. If your fingers are tapered, measure at the point the ring will be worn.
Ideally call to our store in person for the most accurate size but an reasonably accurate finger size helps. We can re-size most of our rings a few sizes in our on-site workshop.