How to get her ring size without asking
This is the most searched question in the category, and it has a slightly annoying answer: you probably do not need to solve it.
Every major retailer resizes for free within a window, and a ring that is one size out is fixed in a week. Getting it wrong is normal and it costs nothing. So if the secrecy is making you anxious, the useful thing to know is that the anxiety is out of proportion to the problem.
That said, here are the methods that work, roughly in order of reliability.
Borrow a ring she already wears
The most accurate method, and the one with the most ways to go wrong.
Take a ring from the correct hand. In most of the UK, US and Australia the engagement ring goes on the left ring finger; in Germany, Russia, India and much of Scandinavia it is the right. Fingers on the dominant hand tend to be slightly larger, so a ring from the wrong hand can easily be half a size out.
Once you have it, you have three options. Take it to a jeweller, who will size it in about thirty seconds. Press it into a bar of soap and take the impression in. Or trace the inside circle on paper, carefully, and measure the diameter.
Then put it back before it is missed. This is the part people get wrong. Take a ring she does not wear every day, and return it the same evening.
Ask her sister or closest friend
Less romantic, more reliable, and it works far more often than people expect.
Someone close to her very likely knows her size, or can find out without arousing suspicion in a way you cannot. They are also usually delighted to be asked, which is worth something. The risk is discretion, so pick the person you would trust with anything else.
If she has a Pinterest board you are not supposed to know about, this same person can probably see it.
Compare against your own hand
Rough, but better than nothing.
Slide one of her rings onto your own finger and mark where it stops with a pen. Then take that measurement to a jeweller or against a printable ring sizer. It gives you a ballpark rather than a size, which is enough to avoid being wildly out.
Just guess
Genuinely acceptable, and more common than you would think.
The average women’s ring size is around a US 6 to 6.5, or a UK L to M. If you know nothing at all, that is the number to use. Slightly large is better than slightly small: a ring that does not fit over the knuckle cannot be worn at all, and the proposal photograph is easier if it goes on.
Things to account for
Wider bands fit tighter. A chunky band needs roughly a quarter to half a size larger than a thin one for the same finger.
Fingers change through the day. They are smaller in the morning and in the cold, larger in the evening, after exercise, and in heat. If you are measuring a borrowed ring this does not matter, but if she has ever mentioned her size in passing, remember it may have been taken at one extreme.
Knuckles. If she has larger knuckles than finger base, the ring has to pass the knuckle and will then be loose. Jewellers solve this with sizing beads, which can be fitted later.
The part that actually matters
Check the resizing window before you buy, and check it against your proposal date.
Some retailers give 60 days of free resizing. Others give a full year. If you are buying two months before proposing, as retailers themselves recommend, a 60-day window may have closed before she has ever put the ring on.
That is the real trap in ring sizing, and it has nothing to do with measuring her finger. Read the resizing terms against your actual timeline, and prefer the longer window if you are buying well ahead.
Also confirm whether the specific setting can be resized at all. Full eternity bands and some pavé settings cannot, because the stones run the whole way round. If you are buying one of those, get the size right first time or accept that a change means remaking the ring.
If you get it wrong anyway
Nothing has gone wrong.
She wears it for the proposal, you send it back, it returns in the correct size a week or two later. Every major retailer handles this routinely and free, within their window. It is one of the most common post-proposal tasks in the industry.
Worth knowing so you can stop worrying about it and go back to the harder question, which is the ring itself.
Policies and terms change; this article was last checked in September 2026. Confirm current resizing terms on the retailer’s own site before ordering. This article contains affiliate links: if you buy through them we may earn a commission at no extra cost to you.