This has got to be the most frequently asked question in the world of jewellery, particularly when it comes to engagement rings. When buying any other type of jewel, it’s pretty much one size fits all, but figuring out her ring size is more difficult, particularly if you want the proposal to be a surprise. 

Because it’s not the kind of thing you can guesstimate, there is plenty of room for error, and if you are buying a vintage ring it’s even more important to get it right (resizing a ring more than once will weaken the precious metal).

Our advice when buying an engagement ring – either new or vintage – is to exchange it for the correct size, or get it resized, after you have proposed. If you walk in to most jewellers, they will happily help you work out the correct ring size for your partner. However, if you have your heart set on a surprise proposal and you are determined to present her with a ring that fits, there are still various options open to you:

Use a ring sizer

Download a PDF version of our ring sizer by clicking here. Before you do, check your print options. DO NOT check the ‘shrink to fit’ or ‘scale to fit page’ option in your print window. This ring sizer should be printed at 100% to ensure accuracy. To double check it has printed at the correct size, measure the outer box and check that the dimensions match those marked on the print out.

For lots of women, an engagement ring is the first ring they wear on this finger. If your girlfriend is one of them, refer to our tips below. Otherwise, when she’s out, borrow a ring that she wears regularly on her ring finger (traditionally the fourth finger on the left hand, including the thumb). Place it over the circles on the ring sizer you have printed out and take a note of the letter that best matches the internal diameter of the ring. Congratulations! You now know her ring size.

Ask her best friend for help

Make her best friend your close ally. Whilst you enquiring about her ring size will definitely arouse suspicion, her girlfriend casually asking her the same question won’t. If it materialises that she has no idea, it's time for plan B.

Suggest a girls' shopping trip

Plan B involves an element of subterfuge. Facilitate a shopping trip with her and a friend, centred around trying on rings. It could be engagement ring focussed or simply a ring trying-on session among friends. Either way, make it her friend’s mission to find out her ring size along the way, ideally with the help of a professional.

Calculate her size based on the size of another finger

This is not the most accurate method, but it is an option if all others have failed. From experience, we can work out her ring size based on the size of another of her fingers. Download our ring sizer and, using the method outlined above, note down the size and email it to us, together with the finger she usually wears the ring on and also whether she is right or left handed (interestingly, our dominant hand is usually slightly bigger).

Always bear in mind

• The most accurate way to calculate your girlfriend’s ring size is for her to have it professionally measured by a jeweller. All other methods are, to a greater or lesser degree, approximations
• Be sure to check the returns/exchanges policy before buying an engagement ring
• Most companies selling antique/vintage jewellery rings offer an exchange/refund policy (including us), but only if a ring hasn’t been resized. As soon as a ring is resized to a custom fit, you will be unable to exchange it or get a refund
• With vintage rings, it is always safest to propose first then have it resized after the proposal. Even if you know it is going to be too small/large, that way she can enjoy the element of surprise whilst also knowing that she can have it resized to the perfect fit afterwards (free of charge, in our case).