To measure ring size at home, wrap a paper strip around the base of your finger, mark where it overlaps, measure that length in millimeters, and divide by 3.14 to get the inside diameter. Then match that diameter to a US ring size chart like the one below.
Measuring your finger with a strip of paper
- Cut a thin strip of paper about as wide as the ring you have in mind. Paper gives a steadier reading than yarn or string, which can stretch.
- Wrap it around the base of the finger that will wear the ring, snug but not tight.
- Mark the point where the end overlaps with a fine pen.
- Lay the strip flat and measure from the end to the mark in millimeters.
- Divide that number by 3.14. A strip of 54.4 millimeters, for example, gives an inside diameter of about 17.3 millimeters.
- Repeat two or three times, then slide the strip loop over your knuckle to make sure a ring that size would get on and off.
Sizing from a ring that already fits
A ring you already wear comfortably on the same finger is the most reliable guide you own. Lay it on a ruler marked in millimeters and measure across the inside, edge to edge, at the widest point. Do not include the metal band itself. That number is the inside diameter, and it goes into the chart directly without any math.
Make sure the ring comes from the same finger and hand, since sizes vary between fingers and your dominant hand can run a little larger. Some jewelers publish printable sizers with circles to match a ring against. If you use one, print it at 100 percent scale rather than fit to page, and check the ruler on the printout before trusting it.
US ring size chart by inside diameter
| US ring size | Inside diameter (mm) | Approximate circumference (mm) |
|---|---|---|
| 4 | 14.88 | 46.7 |
| 5 | 15.70 | 49.3 |
| 6 | 16.51 | 51.9 |
| 7 | 17.32 | 54.4 |
| 8 | 18.14 | 57.0 |
| 9 | 18.95 | 59.5 |
| 10 | 19.76 | 62.1 |
| 11 | 20.57 | 64.6 |
| 12 | 21.39 | 67.2 |
Each whole size adds a little over 0.8 millimeter of diameter, and half sizes fall halfway between the rows. The circumference column is the diameter multiplied by pi, which is the length your paper strip should match. Charts from different jewelers can differ by around a tenth of a millimeter, so when you order, check the seller’s own chart too.
Knuckles, wide bands and time of day
Fingers change size through the day. They swell when warm and shrink when cold, so measure at the end of the day when your hands are warm, not right after a winter walk or a cold shower. Measuring at a few different times and comparing gives a truer picture.
If your knuckle is noticeably wider than the base of your finger, measure both and choose a size in between, so the ring slides on without spinning loosely once it is in place. Band width changes the fit too. Wide bands cover more skin and feel tighter than thin ones of the same size, so many jewelers suggest going up half a size for a wide style.
When to have a jeweler confirm the size
A home measurement is close enough for a fashion ring or a band with a generous return policy. For an engagement ring, an expensive piece, or a wide band, have a jeweler measure with a set of sizing rings, which fit like real rings and account for knuckles in a way paper cannot. Before buying, ask about the resizing policy, since not every design can be resized easily.
Shopping for someone else is trickier, since you cannot wrap a strip around their finger without giving the game away. Borrow a ring they wear on the right finger for an hour, measure its inside diameter as described above, and put it back. If that is not possible, trace the inside edge of the ring on paper and measure the circle instead.
Frequently asked questions
Is it better to size up or down between sizes?
Going up usually makes more sense, because a slightly loose ring still gets past a swollen knuckle and is easier to take off in warm weather. A ring that spins or slides off is a loss risk, though, so ask a jeweler about sizing beads or resizing if the larger size proves too loose.
Are ring sizes the same in every country?
No. The numbered sizes in this chart are used in the United States, Canada and Mexico, while other countries use different systems, such as letters or the inside circumference in millimeters. Converting through the inside diameter, which the chart lists, is the reliable way to match a size from one system to another.
Can your ring size change over time?
It can. Fingers change with weight, age, pregnancy and temperature, and many people find their dominant hand runs a little larger. If a ring that once fit starts pinching or spinning, remeasure at the end of the day and have a jeweler confirm the size before paying for resizing.
How do you measure ring size in centimeters?
Measure the paper strip in centimeters, then multiply by 10 to get millimeters, the unit the chart above uses. A strip of 5.44 centimeters is 54.4 millimeters, which matches the circumference column for a US size 7. Divided by 3.14, it also gives an inside diameter of about 17.3 millimeters.
What is the average ring size for a woman?
Size 6 is the most common. Blue Nile, a large online jeweler, reports that sizes 5 to 7 are the women's sizes it sells most often, with 6 the most popular. That makes a fair starting guess for a gift, but a measurement or a ring she already wears on that finger is far more reliable.
What is the average ring size for a man?
Size 9 is the most common. Blue Nile, a large online jeweler, reports that the men's sizes it sells most often run from 8 to 10.5, with 9 the most popular. Treat that as a rough guide, since a wide band fits more snugly than a thin one, and measure the finger itself before ordering.
