Ring Size Converter

How to Secretly Find Your Partner's Ring Size

You want the ring to fit when they open the box, without giving the surprise away. These methods work, ranked from most to least reliable.

Quick answer

The most reliable trick is to borrow a ring they already wear on the correct finger and measure the inside diameter with a ruler. If you cannot, order a US 6 / UK L½ for women or a US 9 / UK R½ for men and resize later.

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Inside circumference, mm

Inside

Inside

Inside

Inside

Matched inside diameter 17.30 mm · circumference 54.35 mm

The eight methods

  • Borrow a ring they wear on the ring finger and measure the inside diameter with a ruler.
  • Press that ring into a bar of soap or plasticine and measure the impression later.
  • Trace the inside of the ring on paper with a sharp pencil.
  • Slide their ring onto your own finger and mark how far it goes, then have a jeweller size that mark.
  • Ask a friend, sibling or parent who can bring the subject up naturally.
  • Go jewellery shopping 'for fun' and let them try rings on.
  • Check a ring box, receipt or online order history for a size.
  • Buy a cheap costume ring as a gift and see whether it fits.

Watch out for these traps

  • Rings from the right hand run smaller than the left for most people — check which hand you borrowed from.
  • A ring from a different finger is not comparable. A middle-finger ring is often a full size larger.
  • Wide bands are ordered larger than thin bands, so a chunky ring is not a reliable guide.
  • Do not borrow a ring the night before — a missing ring gets noticed fast.

If you have to guess

Guess slightly large. A loose ring can be worn on another finger until it is sized, but a ring that will not go on ruins the moment. Ask the jeweller for a free first resize before you buy.

Frequently asked questions

What is the safest ring size to guess?

A US 6 (UK L½) for women and a US 9 (UK R½) for men are the most common sizes, so they are the safest guesses.

Can a proposal ring be resized afterwards?

Most plain and solitaire bands can be resized by one or two sizes. Eternity rings and tension settings often cannot, so check before buying.

Keep reading

For an expensive ring, confirm the size with a jeweller before ordering — see the ring size FAQs for resizing advice.