Learning Center Guide
Ring Size Chart
US ring sizes are fixed measurements: a size 6 is 16.5 mm across the inside, a size 7 is 17.3 mm. Here's the whole chart in millimeters, centimeters and inches, the UK, European, German, Japanese and Swiss conversions, three ways to measure at home, and how far off each one can put you.
The Chart
US Ring Size Chart: Millimeters, Centimeters and Inches
Find your measurement in the chart and read the US size across. If you haven't measured yet, the three ways to do it are further down. Inside diameter is the width across the middle of the ring; circumference is the distance around your finger.
| US size | Inside diameter (mm) | Inside diameter (in) | Circumference (mm) | Circumference (in) |
|---|---|---|---|---|
| 3 | 14.1 | 0.56 | 44.2 | 1.74 |
| 3½ | 14.5 | 0.57 | 45.5 | 1.79 |
| 4 | 14.9 | 0.59 | 46.8 | 1.84 |
| 4½ | 15.3 | 0.60 | 48.0 | 1.89 |
| 5 | 15.7 | 0.62 | 49.3 | 1.94 |
| 5½ | 16.1 | 0.63 | 50.6 | 1.99 |
| 6 | 16.5 | 0.65 | 51.9 | 2.04 |
| 6½ | 16.9 | 0.67 | 53.1 | 2.09 |
| 7 | 17.3 | 0.68 | 54.4 | 2.14 |
| 7½ | 17.7 | 0.70 | 55.7 | 2.19 |
| 8 | 18.1 | 0.71 | 57.0 | 2.24 |
| 8½ | 18.5 | 0.73 | 58.3 | 2.30 |
| 9 | 18.9 | 0.74 | 59.5 | 2.34 |
| 9½ | 19.4 | 0.76 | 60.8 | 2.39 |
| 10 | 19.8 | 0.78 | 62.1 | 2.44 |
| 10½ | 20.2 | 0.80 | 63.4 | 2.50 |
| 11 | 20.6 | 0.81 | 64.6 | 2.54 |
| 11½ | 21.0 | 0.83 | 65.9 | 2.59 |
| 12 | 21.4 | 0.84 | 67.2 | 2.65 |
| 12½ | 21.8 | 0.86 | 68.5 | 2.70 |
| 13 | 22.2 | 0.87 | 69.7 | 2.74 |
The chart stops at 13 because we do. Size 13 is the largest ring we make, so 22.2 mm across the inside is the top of the range and not a table that ran out of room. If you measure past it, contact us before you order and we'll tell you honestly what we can do on the piece you want.
Women's and Men's Sizes Use the Same Chart
There's no separate women's ring size chart. US sizes are one scale for everyone. Women most often land between 6 and 6½, men between 9 and 10.
That's a range, not a rule. A size 10 on a woman is above average and completely ordinary; plenty of hands wear it. A size 9 is bigger than a size 8, by 2.5 mm around the finger, which is one full row on the chart above. If someone tells you a size sounds large, the chart disagrees with them.
Converting Centimeters and Inches
Centimeters are the millimeter circumference divided by ten. 6 cm is 60 mm, which is a shade over a US size 9. For inches, read the inch columns above or divide millimeters by 25.4.
If you measured 3 inches around, something went wrong. Three inches is 76 mm, past where standard US charts stop. Nine times out of ten it means the paper was measured with the overlap included, or wrapped over the knuckle instead of the base of the finger. Measure again.
International Sizes
International Ring Size Conversion: UK, European, Japanese and Swiss
Find your country's size in its column and read the US size on the left; every ring we make is cut to a US size. Canada uses the US chart with no conversion at all.
| US size | UK & Australia | France / Europe | Germany | Japan | Switzerland |
|---|---|---|---|---|---|
| 3 | F | 44 | 14 | 4 | 4 |
| 3½ | G | 45¼ | 14½ | 5 | 5¼ |
| 4 | H½ | 46½ | 15 | 7 | 6½ |
| 4½ | I½ | 47¾ | 15¼ | 8 | 7¾ |
| 5 | J½ | 49 | 15¾ | 9 | 9 |
| 5½ | L | 51¾ | 16 | 10 | 11¾ |
| 6 | M | 52¾ | 16½ | 12 | 12¾ |
| 6½ | N | 54 | 17 | 13 | 14 |
| 7 | O | 55¼ | 17¼ | 14 | 15¼ |
| 7½ | P | 56½ | 17¾ | 15 | 16½ |
| 8 | Q | 57¾ | 18 | 16 | 17¾ |
| 8½ | R | 59 | 18½ | 17 | 19 |
| 9 | S | 60¼ | 19 | 18 | 20¼ |
| 9½ | T | 61½ | 19½ | 19 | 21½ |
| 10 | T½ | 62¾ | 20 | 20 | 22¾ |
| 10½ | U½ | 63 | 20¼ | 22 | 23¾ |
| 11 | V½ | 65 | 20¾ | 23 | 25 |
| 11½ | X | 66¼ | 21 | 24 | 26¼ |
| 12 | Y | 67½ | 21¼ | 25 | 27½ |
| 12½ | Z | 68¾ | 21¾ | 26 | 28¾ |
| 13 | Z½ | — | 22 | 27 | — |
UK and Australian sizes are letters, not numbers, and they run about one letter per half US size. The European systems are built straight from the finger's measurements: a French or European size is the inside circumference in millimeters, a Swiss size is that circumference minus 40, and a German size is simply the inside diameter in millimeters. So if a European size is quoted as a plain number in the 40s to 60s, the circumference column in the US chart above is already the conversion.
The systems don't land exactly on top of each other, so where a country has no size at exactly that US half size, the chart shows the nearest one; it's never more than a quarter size away, which is inside the tolerance of a string measurement anyway. If you only know your non-US size, the safest move is to give us the letter or number and let us do the conversion.
Print It
Printable Ring Size Chart: Print at 100%, Then Check It
Two different things get called a printable ring size chart. A chart of numbers prints fine at any scale. A printable sizer or circle chart only works at exactly 100%.
Print at “actual size” or 100%, never “fit to page” or “shrink to fit”, whichever chart you use. Then lay any credit card over the printed ruler: a card is 85.6 mm wide by international standard, so if the ruler disagrees, your printer scaled the page and every circle on it is now the wrong size. A 4% shrink drops a size 7 to somewhere between a 6 and a 6½.
The same trap sits on your screen. An “actual size” chart shown on a monitor depends on browser zoom, screen density and operating-system scaling, and phone sizing apps calibrate by asking you to lay a card on the glass. They're useful for checking a size you already measured. They're not a good place to get the number in the first place.
Measure At Home
How Do I Measure My Ring Size at Home?
Three ways, in this order of accuracy: a physical ring sizer, measuring a ring they already wear, then string and a ruler. A jeweler's counter still beats all three.
The Free PrimeStyle Ring Sizer
Ask and we'll mail you a plastic one, free, whether or not you ever order from us; it arrives in 5 to 7 business days anywhere in the US or Canada. It works like a small belt: slip it on, pull it snug, read the size at the marker. Because it sits on the finger the way a ring does, it settles the knuckle question that paper methods can't. Any jeweler has the same tool on the counter, so if there's one nearby you don't have to wait for the mail. Either way this is the most accurate thing you can do without a bench.
Measure a Ring They Already Wear
The quiet method, made for surprises. Borrow a ring that fits the finger you're buying for, then measure the widest distance across the inside in millimeters and match it to the diameter column above. Two cautions. Left and right hands differ by up to half a size, and the dominant hand usually runs slightly larger. And don't trace the ring on paper: a pencil line adds most of a size before you've even picked up the ruler.
The String-and-Ruler Method
Wrap a strip of paper or a piece of string where the ring will sit, mark where it overlaps, and measure to the mark in millimeters. That number is the circumference column above.
Here is what the chart does not show you. Look at the gap between two rows: a full US size is about 2.5 mm of circumference and a half size is about 1.2 mm. That's the width of a pen line. Pull the string a millimeter tighter than you should and you've moved the answer nearly half a size, and almost everyone pulls too tight, so string readings usually come back small. It's a fine way to get in the neighborhood. It's not a way to be certain. Check it against a second method before anything gets cast.
Get It Right
Three Rules That Decide Whether It Fits
A ring that fits slides on with a little resistance and comes off with a little effort. These three rules are what stands between a measurement and that.
Measure at the end of the day
Fingers are smallest on a cold morning and largest at the end of a warm day, and the swing is real: the same finger can read a half size apart between the two. Measure in the evening, indoors, at room temperature. That's the size the ring has to live with.
Size past the knuckle, not to it
If the knuckle is wider than the base of the finger, size so the ring clears the knuckle. A ring that won't go on isn't a ring. It should pass with real effort, then settle. Accept that it will have some play at the base, and know that a ring with weight on top, a big center stone or a wide halo, will slowly rotate toward the palm on a loose fit.
Width and comfort fit pull opposite ways
Decide these two together, never one after the other. A band 6 mm or wider covers more finger and wears about a half size tighter. Comfort fit, the domed inside most of our bands are made with, slides on easier and runs about a half size large. On a wide comfort-fit band the two cancel, so you order the size you measured. If only one of them applies, move a half size: up for a wide band that isn't comfort fit, down for a narrow one that is.
Between Two Sizes
Between Two Sizes, Order the Quarter Size
Order the quarter size. A 6¼ is a real size here, not a special request, so you don't have to round at all. If you'd rather stay on the whole and half sizes, take the larger one: a slightly loose ring gets worn today, and a tight one never gets worn at all.
There's a cost to being wrong, and it's worth knowing before you order rather than after. Resizing is a paid service, not a warranty item, and here's the price: $49.99 on a gold ring, $69.99 on platinum. The ring ships back to us, spends 3 to 5 business days at the bench, and ships out again. It also destroys anything engraved inside the shank, so an engraved ring gets engraved a second time, $29.99. The one time we don't charge for the work is when the mistake is ours and we shipped the wrong size; then you cover the return shipping and nothing else.
Some rings are not resized at all. Eternity bands, full-pave bands and channel-set bands are built to one exact size on purpose, because that's what lets the diamonds run all the way around at even spacing with no gap at the bottom. Change the size and the whole band is remade rather than stretched. That's not a reason to avoid them; it's the reason they look the way they do. It just means the size has to be right the first time. Our Setting Styles guide covers which settings sit where, and the eternity rings themselves are here.
On a custom piece we ask you to reconfirm the size at the 3D approval stage, before anything is cast. A size change caught there is free. A size change caught after casting is a resize.
Without Asking
How to Get Her Ring Size Without Asking
Borrow a ring she already wears on that hand and measure the inside diameter against the chart. It's the most accurate thing you can do without saying a word.
The move that works even better is asking one other person. Her mother, her sister, her closest friend: one of them knows, one of them has borrowed a ring, and none of them will tell her. That single question solves this more often than any measuring trick on the internet.
If neither is possible, order 6½. It sits in the middle of the range most women wear, it's easier to take a ring in than to let one out, and you'll be paying for a resize afterward rather than gambling on the proposal itself.
One warning about timing. If the date is close, a made-to-order ring is made to order, so the size you choose is the size that gets cast. Ready to ship pieces are already finished, which means they come in the sizes on the shelf rather than yours. Whichever route you take, contact us before you order and we'll tell you honestly which one makes your date.
Once you have the number: engagement rings, bridal sets, wedding bands, eternity rings and men's rings. Every made-to-order piece is cut and set to the size you give us, in our own US factory.
Quick Answers
Asked every day at our counter
Will losing 10 pounds change my ring size?
I'm between two sizes. Which do I pick?
Can the ring be resized after the proposal?
It's a surprise and there's no ring to borrow. What now?
How big is a size 7 ring?
I only know my UK size. What do I order?
Not Sure?
We'll mail you a ring sizer, free.
Tell us where to send it and a plastic sizer goes out to you, with nothing to buy and no order attached. Already measured a borrowed ring and not sure what you're looking at? Send us the millimeters and we'll read the chart with you. Either way, contact us and someone who sizes rings for a living will answer.