Ring Size Chart and Printable Ring Sizer

A US ring size is a number for the inside of the band, and every ring size chart turns it into millimeters: on Tiffany's chart a US 6 is 16.5 mm across and 51.9 mm around. The sizer below prints at true scale, with a calibration rectangle so you can prove it did, because a printed ring sizer that came out at 97 percent will hand you the wrong number without ever telling you.

Ring Size Chart, US 3 to 13.5

The figures below are Tiffany & Co.'s published chart, which is the only one we found that publishes both a diameter and a circumference across the whole range. The inch columns are our own arithmetic from those millimeter figures, not Tiffany's own numbers. US 13.5, which Tiffany does not publish, is GIA's and Larson Jewelers' figure.

How to Read It

Diameter is measured across the opening, circumference around it. The quickest way to tell which number you are holding: anything in the teens is a diameter, anything in the 40s to 70s is a circumference. In centimeters, move the decimal point one place, so a 51.9 mm circumference is 5.19 cm.

Ring Size Chart for Women

There is no separate women's scale. The same US numbers apply, and women's rings are simply stocked across a narrower part of the range, roughly US 3 to 10. No published survey establishes an average women's size, which our guide to the average ring size for women sets out in full, and the men's side is covered in the men's ring size chart. Anyone who quotes you a single average is quoting one retailer.

The Charts Disagree, and Here Is by How Much

Nine published charts were read for this page and they do not match each other. The disagreement is small, but it is real, and knowing it exists is worth more than a false decimal place.

The spread is the gap between the highest and lowest published figure at that size, and computing it is our own arithmetic on their numbers. The widest is 0.7 mm of circumference at US 10.5 and US 11.5. For scale, half a US size is about 1.27 mm of circumference, so the charts differ by more than half of a half size. Fred Meyer Jewelers is the low outlier at every size it covers; leave it out and the spread never passes 0.2 mm.

Why They Disagree

Because the US scale has never had defined dimensions. The Bureau of Standards looked for them in 1921 and reported the result plainly in Circular 43: "All attempts to find any printed statement as to what the dimensions of the various sizes are supposed to be, have been unsuccessful." Nothing has replaced that since. ISO 8653:2016 standardizes the ISO scale, where the size number is the circumference in millimeters, and it publishes no US table at all.

The One Formula and the One Tolerance

Only one source we read publishes a formula. Wikipedia's ring size article gives the relationship to the ISO scale as a circumference of 2.55 times the US size plus 36.5, and a diameter of 0.8128 times the US size plus 11.63. Its own equivalency table does not match it exactly at every row, which is itself part of the picture.

Only ISO 8653:2016 publishes a tolerance, and it is easy to misread: the ±0,02 mm applies to the ring stick, the metal gauge a jeweler measures with. It is not a tolerance on a ring, on a finger, or on a printed chart, and nobody should quote it as one.

Which Number Should You Trust?

Any of them, as long as you do not mix them. At US 12.5 and 13 the diameters agree to a hundredth of a millimeter; at US 6 there are three published circumferences. Kay is not wrong and Tiffany is not right, because there is no arbiter to make either so. The practical rule is to take both numbers from the same chart, since the damage comes from pairing one jeweler's diameter with another's circumference.

That is not a hypothetical. Google's own AI overview for "ring size chart", on the day this page was written, gave US 8 as 18.2 mm across and 57.0 mm around. A circle 18.2 mm across is 57.2 mm around, so the two numbers cannot describe the same ring: it had taken the diameter from one chart and the circumference from another.

How to Measure Ring Size at Home

A Paper Strip or a Piece of String

Cut a thin strip of paper, wrap it around the base of the finger, mark where it overlaps, then lay it flat against a ruler and read the millimeters. That is a circumference, so read it against the third column of the chart. GIA warns that string and paper stretch and curl, so pull it snug rather than tight and do it more than once.

Measuring a Ring You Already Own

Lay the ring over the printed circles above and find the one that matches the inside edge of the band. The inside edge is the whole measurement, and reading to the outside edge is the common way to land a size too large. A ring measured this way tells you the size of the finger it currently fits, which is not always the finger you are buying for.

When to Measure

At the end of the day, when hands are at their largest, and when you are warm rather than cold. Fingers change with temperature and activity, which is why a measurement taken once in the morning is the least reliable version you can get. Measure on two different days and take the larger reading.

Why Your Printed Sizer Comes Out Wrong

Most printable sizers are PDFs, and a PDF is exactly what triggers the scaling controls in a browser's print dialog. Chromium's own documentation notes that its fit-to-page options appear only for PDF documents, so an HTML page like this one prints at 100 percent by default and offers no fit option to get wrong. That is why this sizer is a web page rather than a download.

The Card Check, and What It Actually Guarantees

A bank card is a useful ruler because its size is specified: ISO/IEC 7810 defines the ID-1 format as nominally 85,60 mm by 53,98 mm. Nominally is the operative word. The standard's own tolerances put an unused card between 85,47 and 85,72 mm wide, and a used one between 85,37 and 85,90 mm, so the check proves your print is within a few tenths of a millimeter, not that it is exact. Use the long edge, and ignore the corner radius and the thickness, which are too loose to test anything.

A4 Against US Letter

The artwork here fits inside both sheet sizes, which is the case every competing sizer ignores. It also means this page never declares a paper size in its stylesheet: telling the browser the page is A4 invites it to shrink the whole thing to fit a Letter tray, quietly, at about 94 percent.

If the Rectangle Comes Out Wrong

Do not reprint blind. Measure the printed rectangle, type that number into the box in step 1, and everything on the page rescales to compensate, on screen and on the next print. We have not measured how accurate this tool is in the hands of readers, so we make no claim about it: the rectangle is the check, and it either matches a card or it does not.

What the Number Does Not Cover

Wide Bands Fit Tighter

A wider band covers more skin and usually feels tighter at the same measured size, and the sellers disagree on where that starts to matter. Brilliant Earth puts it at bands over 4 mm, GIA at 4 to 5 mm, Fred Meyer Jewelers at 6 mm and Gabriel at 10 mm. There is no consensus threshold to give you, only the direction: wide means size up, and try the exact profile if you can.

A Knuckle Wider Than the Base

Measure both, and take a size between the two: big enough to pass the knuckle, small enough not to spin. If the gap is large, GIA describes sizing beads and hinged shanks as the jeweler's answers, both of which are decisions about the ring rather than about the number.

Comfort Fit Is a Different Measurement

A comfort fit band is domed on the inside, so it touches the finger differently from a flat one. Sellers contradict each other about whether to order a smaller size for one, and Brilliant Earth says in as many words not to do it automatically.

UK, EU and ISO Equivalents

The conversions disagree more than the millimeters do. A US 6 is published as a UK L by GIA, a UK L½ by Brilliant Earth and a UK M by Tiffany, all read on the same day. There is no single right letter to give you, so if you are ordering from a British or European jeweler, send the millimeters and let them convert, or ask which chart they use. The ISO size is the simplest of the three, because on that scale the size number is the inside circumference in millimeters: a 51.9 mm finger is an ISO 51.9.

Frequently Asked Questions

Can My Phone Measure My Ring Size?

Only if you calibrate the screen first, because pixel density differs between devices. Lay a bank card against the rectangle in step 1 and adjust until they match, then use the on-screen circle. Without that step a phone is measuring in pixels of unknown size, which is why a photo of a ring cannot give you a size on its own.

How Do I Measure My Ring Size Without a Ring Sizer?

Wrap a strip of paper around the base of the finger, mark the overlap, and measure the marked length against a ruler in millimeters. That figure is the inside circumference, so read it against the third column of the chart above. Do it at the end of the day and repeat it once before ordering.

Is There a Standard Ring Size Chart?

Not for the US scale. ISO 8653:2016 standardizes the ISO scale, in which the size is the circumference in millimeters, but it publishes no US conversion. The Bureau of Standards reported in 1921 that no printed statement of US size dimensions could be found, and the charts still differ by up to 0.7 mm today.

What Is the Difference Between Ring Diameter and Circumference?

Diameter is the distance straight across the inside of the band, circumference the distance around that opening. Circumference is about 3.14 times the diameter. Charts publish both, and the practical rule is to take both figures from the same chart rather than pairing one jeweler's diameter with another's circumference.

Should I Size Up or Down If I Am Between Sizes?

Up, in most cases, and more confidently if the band is wide. A ring that will not pass the knuckle is unwearable while a slightly loose one can be tightened with beads or a sizing bar. Check the seller's resizing terms before ordering, since some bands cannot be resized at all.

How Accurate Is a Printed Ring Sizer?

It depends entirely on whether it printed at true scale, which is the part most sizers never let you check. Once the calibration rectangle matches a bank card, the remaining error is the paper strip itself: it stretches, and a finger changes size through the day. Treat the result as a starting point to confirm with a jeweler.

Sources

• S. W. Stratton, Circular of the Bureau of Standards No. 43, "Jewelers' and Silversmiths' Weights and Measures", 2nd edition, United States Department of Commerce, 1921, section VII "Ring Sizes".
• International Organization for Standardization, ISO 8653:2016, Jewellery — Ring-sizes — Definition, measurement and designation, 2016, read from the public preview of the standard.
• International Organization for Standardization and International Electrotechnical Commission,ISO/IEC 7810, Identification cards — Physical characteristics, clause 3.5 and Figure 1, for the ID-1 format.
• Tiffany & Co., Ring Size Guide, undated, accessed 11/09/2026.
• GIA 4Cs, How to Determine Ring Size: Tips and Ring Size Chart, accessed 11/09/2026 via the Internet Archive, because the live page blocks scripted requests.
• Brilliant Earth, Ring Size Chart andRing Width Guide, undated, accessed 11/09/2026.
• Kay Jewelers, Ring Size Guide; Jared,Ring Size Guide; Larson Jewelers,Ring Sizing Chart for US Sizes; Fred Meyer Jewelers, ring size chart. All undated, accessed 11/09/2026.
• Wikipedia, Ring size, accessed 11/09/2026, for the published US-to-ISO formula.
• United States Mint, coin specifications, for the 24.26 mm quarter used as the second calibration reference.

Researched from published charts and standards, not from testing. We do not sell rings and nothing on this page is a paid placement.