Ring size tool

What a ring size really is

A ring size is simply a name for the hole in the middle of the ring. That hole can be measured in two ways: straight across it, which is called the diameter, or all the way round its edge, which is called the circumference.

Each country names that hole its own way. The US, Canada and Mexico use numbers, and the UK, Ireland and Australia use letters. Most of Europe uses the distance around the inside of the ring, in millimetres. So a ring that measures 54 millimetres around is a European size 54. You never have to change one into another yourself, because the tool shows them all together.

So the same ring has a different name in each country. A typical women's size, for example, is called 7 in the US, N½ in the UK, 54 in Europe and 14 in Japan.

Using the ring sizer on your screen

Screens come in all sizes, so the tool first needs something of a known size to measure against, and a bank card is perfect. Hold your card flat against the card picture on the screen. Move the slider under the picture until it is the same height as your real card. When they match, tap Done. Your phone or computer remembers it for next time.

Once the card is matched, you can measure in two ways. Lay a ring that already fits on the circle, then make the circle bigger or smaller until it lines up with the inside of the ring. Or, if you measured your finger with a paper strip, tap My finger and type the strip's length.

Finding your size with a paper strip

All you need is a strip of paper or some string, a pen, and a ruler with millimetre marks. Blue Nile, a large online jeweller, suggests 3 steps:

1. Wrap the paper or string round the bottom of your finger, close but comfortable.
2. Mark with the pen where the two ends meet.
3. Lay it flat next to the ruler and read the length up to your mark.

Type that number into the tool exactly as it is, and your size appears. Start the strip at the ruler's zero mark and count the small spaces up to your pen mark: each small space is one millimetre.

Blue Nile suggests measuring later in the day, once your fingers are warm. Fingers are a little thinner first thing in the morning and in cold weather, and slightly bigger on hot, sticky days. The hand you write with is often slightly bigger too. If your knuckle is wider than the bottom of your finger, measure round the knuckle as well.

Is an app needed to find a ring size?

No. The tool works right here on the web page, on a phone or a computer, and there is nothing to install. The card setting is kept on the device you used.

Common sizes and how they convert

Average sizes give you a rough idea, but measuring tells you your own size. The Antique Jewellery Company, a UK jewellery shop, says most women wear a US 6 to 7, often 6.5. Most men wear a US 10 to 11, and 10.5 is the most common.

Here are those sizes with their UK and European (EU) names. A size ending in .5 or ½ is a half size: US 6.5 means "6 and a half", and N½ means "N and a half".

Japan and India have their own numbers as well. A US 7 is 14 in both countries, and a US 10 is 20 in Japan and 22 in India.

Checking your size against a ring you already own

The easiest start is a ring you already wear on the same finger as the new one. Lay it on the circle, or use a ruler to measure straight across the inside.

Check first that this ring really fits well. Jewelers Mutual, a company that insures jewellery, explains it simply: a good fit slides on easily, feels a little tight going over the knuckle, and then sits snugly at the bottom of the finger without hurting. If another person can pull it off without effort, or a shake of the hand sends it over the knuckle, it is too loose.

If you are between two sizes, the bigger one is the safer choice. Wide rings feel tighter than thin ones. If the band is wider than about 4 millimetres, choose half a size larger, for example US 7½ instead of US 7. If your knuckle is large, pick the bigger size too, so the ring can pass over it.