Ring size is defined by the inside circumference of the band. In the US system, a size 6 measures 51.9 mm around the inside and 16.51 mm across; a size 7 measures 54.4 mm and 17.32 mm. To find your size at home, wrap a strip of paper around the base of your finger, mark where the ends overlap, measure that length in millimeters, and match it to the chart below.

Last updated: October 2026

What is my ring size? Find it in under two minutes

If you have a ring that already fits the correct finger, measure straight across the inside of the band and use the diameter column. If you do not, use a paper strip and the circumference column. Both routes land on the same chart.

Barkev's makes every ring in full, half and quarter sizes, and in eighth and sixth sizes when a fit needs it, at no additional cost. If your measurement falls between two sizes, order the larger of the two.

Ring size chart: US sizes in millimeters and inches

This is the complete US and Canadian scale in half sizes. The relationship is arithmetic rather than arbitrary: each full size adds 0.032 inches (0.81 mm) to the inside diameter, which works out to 2.55 mm of inside circumference. The formula behind every row is inside diameter in inches = 0.458 + (0.032 × size).

Sizes 6 and 7 are highlighted because they sit in the middle of the range most engagement rings are ordered in, and because they are the sizes most American jewelers hold as studio samples. That makes them a useful reference point, not a prediction about any individual finger.

Quarter sizes fall exactly between the rows above, adding 0.008 inches (0.20 mm) of diameter each.

International ring size conversion chart

Ring sizing is not one system. It is five or six systems that describe the same piece of metal in different units, which is why a conversion table is necessary rather than merely convenient.

The international standard, ISO 8653:2016, defines ring size as the inside circumference in millimeters, which is why a European 54 is simply a band measuring 54 mm around the inside. British and Australian sizes use letters instead, spaced 1.25 mm of circumference apart. The table handles the rest.

Japanese and Chinese sizes are given as the nearest equivalent rather than an exact match, because that scale does not divide at the same intervals as the US scale. Where a conversion lands between two sizes in any system, the larger size is the safer order.

One caveat applies to every conversion table, including this one. Ring sizing has never been fully standardized between manufacturers, a gap the US Bureau of Standards already noted in a 1921 circular, so two jewelers can both call a band a size 7 and finish a fraction of a size apart. Record the millimeter figure alongside the size number and the ambiguity disappears.

What your measurement means

If you have already measured and want the number translated, find your measurement here. These are circumference figures, meaning the distance around the finger or around the inside of the band.

A few measurements come up often enough to state directly. A 6 cm circumference is approximately a US 9¼. A 6.5 cm circumference is approximately a US 11¼. A 2.5 inch circumference is approximately a US 10½. A 7 cm circumference is approximately a US 13.

If you measured across a ring rather than around a finger, that figure is the diameter, and it belongs in the second column of the main chart above instead.

How to measure your ring size at home

Four methods, in order of how reliably they land on the correct size. The first is the most accurate thing you can do without a jeweler, because it measures a finished object rather than soft tissue.

Method 1: measure a ring that already fits

Take a ring the wearer currently wears on the intended finger. Lay it flat and measure the inside of the band at its widest point, from inner edge to inner edge, using a ruler with millimeter markings. That figure is the inside diameter. Match it to the diameter column in the chart above.

Measure the inside, not the outside, and ignore the thickness of the metal. A 2 mm error in diameter is roughly two and a half ring sizes, so this is the step worth doing twice.

Method 2: a paper strip and a ruler

Cut a strip of paper about 6 mm wide and 100 mm long. Printer paper works; anything that stretches, including string, thread and ribbon, does not. Wrap it around the base of the finger, snug but not compressing the skin, and mark where the leading edge overlaps. Unwrap it, measure from the end to your mark in millimeters, and read that against the circumference column.

Then check one thing before you trust the number: slide the loop up over the knuckle at the width you marked. If it will not pass, the measurement is too small to wear, whatever the chart says. More on that below.

Method 3: the printable sizer

A printed sizer removes the ruler and the arithmetic from the process. It is accurate when the page prints at true scale and misleading when it does not, because home printers scale documents by default. How to print and verify one is covered below.

Method 4: estimating without measuring

There is no accurate way to determine a ring size without measuring something. If you have no ring and no tape, the usual fallbacks are comparing against your own finger, borrowing a ring that fits a different finger, or ordering from a mid-range size and resizing afterwards. Treat all three as placeholders rather than answers.

If the ring is a surprise and you cannot measure directly, the approaches in the surprise proposal section are more likely to work than guessing.

Printable ring sizer: print it, check it, then use it

The file is three pages. Page one is the cut-out paper sizer with its calibration box. Page two has actual-size circles for measuring a ring you already own, plus the five things that shift a reading. Page three is the full chart with international conversions.

A printed sizer is only as accurate as the printer that produced it. Most printers apply "fit to page" or "shrink to printable area" by default, which can scale a page by three to five percent. On a ring sizer, a four percent error is close to a full size.

Printing it correctly:

1. Open the PDF in a dedicated reader rather than a browser preview.
2. Set scaling to 100% or Actual size. Turn off "Fit to page," "Shrink oversized pages" and "Auto-rotate and center."
3. Print on standard Letter or A4 paper. Do not use photo or glossy stock, which can distort under heat.

Then verify it, which is the step most guides leave out. The sizer has a calibration box printed on it. Lay any credit card or debit card along that box. Credit and debit cards are manufactured to a single international standard, ISO/IEC 7810 ID-1, at 85.60 mm × 53.98 mm, which makes the card in your wallet an accurate ruler that you already own. If the long edge of the card matches the calibration box exactly, the page printed at true scale. If it overhangs or falls short, the page scaled, and the sizer will give you the wrong size. Correct the print settings and print it again.

Using it:

1. Cut along the outer line, then cut the narrow slot where marked.
2. Thread the pointed end through the slot to form a loop.
3. Slide the loop onto the finger and pull it snug at the base, without compressing the skin.
4. Work the loop over the knuckle and back. It should pass with mild resistance in both directions.
5. Read the size at the edge of the slot.

The paper will crease and lose a little tension after a few passes. Read it on the second or third fitting rather than the sixth.

Five things that change the reading

Fingers are not fixed. The same finger measures differently depending on when and under what conditions you check it, which is why one careful measurement taken at the wrong moment can still produce the wrong ring.

Time of day. Fingers are at their smallest in the morning and largest in the late afternoon and evening. Measuring mid to late in the day gives a size that will be comfortable at the finger's typical maximum rather than its minimum.

Temperature. Cold constricts; heat and humidity swell. A measurement taken with cold hands, in winter, or straight after coming indoors will read small. One taken after exercise, a hot shower, a long flight or a salty meal will read large. Aim for a normal resting temperature.

The knuckle. This is the variable that decides whether a correctly sized ring can actually be worn. If the knuckle is considerably larger than the base of the finger, the ring has to clear the knuckle to go on, then sits loose below it. The band must be sized to pass the knuckle. The looseness at the base is then solved at the bench with sizing beads or a fitted insert rather than by ordering a smaller ring.

Band width. A wider band contacts more of the finger and fits more closely than a narrow one at the same nominal size. Jewelers conventionally allow a quarter to half size up for bands wider than about 6 mm. If your measurement came from a thin ring and you are ordering a wider wedding band, account for the difference.

Which hand. The dominant hand is often marginally larger. Measure the finger the ring will actually be worn on, on the hand it will be worn on.

Measuring for a surprise proposal

Measuring someone else's finger without explaining why is the most common sizing problem in engagement ring buying, and it has better solutions than guessing.

Borrow a ring she already wears. The most reliable option. Take a ring from the correct finger, measure the inside diameter with Method 1, and return it. If you can only borrow it briefly, press it into a bar of soap or a piece of modeling clay and measure the impression later.

Use a ring from another finger and adjust. Less precise, but workable. A ring worn on the right ring finger is usually within half a size of the left. An index finger runs larger, a pinky considerably smaller. Note which finger it came from so the difference can be accounted for.

Ask someone who would already know. A close friend, a sibling or her mother frequently knows the size, or can find out without raising the question.

Order at a sensible size and plan to resize. If none of the above is possible, order in the middle of the likely range and treat resizing as part of the plan rather than a failure of it. Choosing a setting that resizes easily matters more here than choosing the right number, which is covered below.

Average ring size for women

Most women's engagement rings are ordered in a size 5 to 7, and size 6.5 is the single most common answer to this question. If you need one number to work from and have no way to measure, start there.

Use it as a starting point rather than a conclusion. An average describes a population, not the person you are buying for, and the gap between a size 5 and a size 7 is just over 5 mm of circumference. That is the difference between a ring that slides off and one that will not go on.

How much weight to give the average depends on what else you know:

If you are ordering on a guess, two decisions matter more than the number itself. Pick a setting that resizes easily, which rules out the designs listed in the next section. And if you are torn between two sizes, take the larger one, because a ring that is slightly loose can be worn until it is adjusted while one that will not pass the knuckle cannot be worn at all.

One caution about the statistics you will find on this topic. Searching for an average ring size returns confident, specific-sounding figures: that a quarter to a third of American women wear a size 6, that ninety percent fall between 4 and 8, that eighty percent of brides need their ring resized. We went looking for the data behind those claims and could not find any. The pages publishing them cite either nothing at all or statistics about something else, such as national height and weight averages. The resizing figure traces back to a single article that states it in its own headline with no study attached. The 5 to 7 range above reflects what jewelers actually stock and cast, which is a real pattern in the trade, but treat any percentage you see on this subject as an estimate rather than a measurement.

If the size is wrong

Most rings can be resized, and a correctly built one can usually be adjusted by up to one or two sizes in either direction without any visible change to the design.

That range is the practical limit, and it is worth understanding before you order. Resizing works by removing a section of the shank and rejoining it, or by cutting it and adding metal. Within a size or two, the band's proportions, the balance of the head and the spacing of any side stones are unaffected. Past that, the geometry stops cooperating: sizing down too far thickens and distorts the lower shank and can pull side stones out of alignment, while sizing up too far thins the metal where it was stretched or adds a visible seam. A three or four size change is usually a request to rebuild the ring rather than alter it, and on an engagement ring the better answer is almost always a remake or an exchange at the correct size.

So the goal is not to order perfectly. It is to order within a size or two of correct, which any of the measuring methods above will achieve comfortably.

Every Barkev's ring comes with free resizing for the first 30 days after it arrives, on any design that can be resized. The work is done in our own Los Angeles workshop, the same one the ring was made in, which is also why we can build it to your exact size to begin with. We have been designing and handcrafting rings here since 1981.

Some designs cannot be resized, and this is structural rather than a matter of policy:

• Eternity bands. Stones run the full circumference, so there is no plain section of metal to cut and rejoin. Changing the size means rebuilding the ring with a different number of stones.
• Full pavé, channel-set and bezel-set shanks. Where settings continue around most of the band, the same constraint applies to the portion that is set.
• Tension settings. The stone is held by the spring force of the metal, and altering the circumference changes that force.

For these, ordering the correct size at the outset matters, and exchanging within the return window is normally the better route than attempting an alteration. If you are unsure whether a particular design can be adjusted, ask before ordering.

For what resizing involves outside the free window, including what drives the cost on different metals and settings, see our guide to ring resizing costs.

Frequently asked questions

Ready to find the ring

Once you have your size, browse engagement rings, all handcrafted in our Los Angeles workshop and made to your exact size at no additional cost.

If you are choosing a center stone as well, our diamond size guide covers how carat weight translates to millimeter dimensions across shapes, which is a separate question from how the band is sized.

Still need to measure? Download the printable ring sizer (PDF), or email us at the address on our contact page and we will talk it through.

Sources

• Inside diameter and circumference values derived from the US sizing formula and cross-checked against published tables at ringsizes.biz
• ISO 8653:2016 definition, the 1987 BSI conversion of UK letter sizes to metric, international system definitions and the 1921 US Bureau of Standards circular: Ring size, Wikipedia
• Credit and debit card dimensions, ISO/IEC 7810 ID-1: ISO/IEC 7810, Wikipedia