Buying a ring as a surprise creates a small practical problem: you need a measurement from someone you cannot ask. The good news is that it is solvable, and several of the methods below are far more accurate than guessing. The better news is that ring sizing is forgiving in one direction — so even a method that gets you close is usually enough.
The methods for how to find a ring size without asking are ranked by how accurate they tend to be. Use the highest one available to you, and read the section on sizing up before you buy. For more sizing guides, see our Size Guides section.
Six Ways to Find a Ring Size Without Asking
1. Borrow a Ring She Already Wears
Take one she wears on the same finger, ideally the same hand, and either take it to a jeweller or measure its inside diameter yourself. Return it before it is missed.
Accuracy: high, if it is worn on the same finger.
2. Measure the Inside Diameter of a Ring
Lay a ruler with millimetre markings across the inside of the ring at its widest point, from inner edge to inner edge. That number converts directly to a ring size.
Accuracy: good, if you measure carefully. Half a millimetre is roughly half a ring size, so take the reading twice.
3. Press a Ring Into Soap or Wax
Press the ring into a bar of soap or a piece of softened wax to leave a clean impression of its inner circle, which a jeweller can read.
Accuracy: good.
4. Ask a Friend or Family Member
Someone close may already know her size, or can find out naturally — trying on rings together is an easy excuse.
Accuracy: depends entirely on the source.
5. Compare Against Your Own Fingers
Slide one of her rings onto your own fingers and note exactly where it stops. A jeweller can size that finger for you afterwards.
Accuracy: fair, and much better than guessing.
6. Estimate From General Hand Size
The least reliable method, and one to use only when nothing else is possible.
Accuracy: low. Use the size-up rule below.
Measuring a Finger Directly
If you ever do get the chance to measure her finger — or you are measuring your own — the string or paper method is quick and needs nothing special. Wrap a thin strip of paper around the base of the finger, mark where it overlaps, and measure the length in millimetres. That is the circumference, which converts to a ring size.
Things That Change a Ring Size
- Temperature — fingers are smaller in the cold and larger in the heat
- Time of day — fingers tend to be slightly larger later in the day
- Which hand — the dominant hand is often slightly larger
- Knuckles — a ring has to pass over the knuckle; a large knuckle and a slim finger need a size that clears one and does not spin on the other
- Band width — a wide band fits more snugly than a thin one in the same size
Converting What You Have Into a Size
Ring sizes are expressed differently around the world. The US uses numbers, the UK uses letters, and much of Europe uses the inside circumference in millimetres. The same ring can carry three different labels depending on where it is sold, which is why converting before ordering matters.
Enter the inside diameter from a borrowed ring, or a circumference from a paper strip, and the converter gives the size in every major system. There is also a printable sizer if you can borrow a ring for a minute.
When You Are Not Sure: Size Up
A ring that is slightly large can often be sized down, or fitted with a small sizing insert. A ring that is too small can only be sized up so far, depending on the metal and the design.
Rings with stones set all the way round — eternity bands — often cannot be resized at all, so accuracy matters most for those. If you are buying one of these and are not confident of the size, a plainer design may be the safer surprise.
If the ring is gold or silver, our guide to gold or silver for your undertone helps you choose the metal, and European jewellery brands worth knowing covers where to look. Planning a wedding? See wedding dress shopping: what to expect. And if she is between two ring sizes, the same logic as clothing applies — see what to do between sizes.
Choosing the Ring as Well as the Size
Once the size is settled, the metal and the style matter as much. The undertone test helps decide between gold and silver, and the colour analysis quiz shows which stone colours sit best with her colouring. For earrings or a matching set, earrings by face shape covers proportion, and the face shape detector works it out from measurements.
If you are buying gloves as part of a winter gift, the same measure-first approach applies — the glove size calculator works from a hand measurement.
Frequently Asked Questions
How can I find her ring size without asking?
Borrow a ring she wears on the same finger and measure its inside diameter, or have a jeweller size it. Both are accurate enough to buy from.
Should I size up or down if I am unsure?
Up. A ring that is slightly large is usually easier to adjust than one that is too small.
Can any ring be resized?
Most plain metal bands can be resized within a size or two. Eternity bands with stones all the way round often cannot.
Is ring size the same on both hands?
Often not. The dominant hand is frequently slightly larger, so borrow a ring from the same hand if you can.
Is tracing a ring on paper accurate?
Not very. The pencil line adds width and the outline is rarely even. Measure the inside diameter with a ruler instead.
For background on how ring size systems differ between countries, see ring size, and for independent guidance on buying rings, the Gemological Institute of America.