Wedding Band Education

Ring Size Guide: US, UK & EU Conversion Chart + How to Measure Your Ring Size at Home

Wedding bands are worn every day, for life — which makes getting the size right more important than for almost any other piece of jewelry you'll ever buy. This guide covers everything you need: a complete international ring size conversion chart (US, UK/Ireland/Australia, EU, and Japan), four accurate ways to measure your size at home, and the sizing details that matter specifically for wedding bands — width, comfort fit, matching his-and-hers sets, and eternity or diamond-set styles that can't be resized as freely as a plain band.

If you already know your size in one system, jump straight to the conversion chart. If you're starting from zero, jump to how to measure your ring size at home.

International Ring Size Conversion Chart

Every major jeweler's chart is built on the same underlying physical measurement: the inside diameter and inside circumference of the ring, in millimeters. The table below follows the ISO 8653 international standard, so you can convert confidently between the US, UK/Ireland/Australia/New Zealand/South Africa, EU, and Japan/China systems.

Need a size below 3 or above 15, or a quarter size in between? Our wedding band specialists can special-order and hand-finish sizes outside the standard range — just ask when you place your order.

How to Use This Chart

1. Know your size in one system? Find it in any column and read straight across the row for the equivalent size everywhere else.
2. Only have a millimeter measurement? Find the closest diameter or circumference value in the last two columns, then read left for your US size.
3. Between two sizes? Size up, not down — especially for wider wedding bands (see the width section below). A slightly loose ring is far more comfortable day-to-day than one that's tight.

Ring Sizing Systems Explained

US & Canada use a numerical scale from about 3 to 16, with half and sometimes quarter sizes. Each whole size increases the inside diameter by roughly 0.8mm. This is the system all of our rings are manufactured and listed in.

UK, Ireland, Australia, New Zealand & South Africa use an alphabetical scale, A through Z, then Z+1, Z+2, and so on for larger sizes. A UK size is not directly interchangeable with a US number of the same digit — always convert using the chart, not by assumption.

EU (continental Europe) sizing follows the ISO 8653 standard and is based directly on the inside circumference of the ring in millimeters, which is why EU sizes are numbers in the 40s through 70s rather than the 3–15 range used in the US.

Japan & China use their own numerical scale (roughly 1–30), also based on inside circumference, but numbered differently from the EU system — don't confuse a Japanese size 14 with a EU size 14, they're not the same measurement.

How to Measure Your Ring Size at Home (4 Methods)

Method 1: The String or Paper Strip Method

The simplest option, and reasonably accurate if you're careful:

1. Cut a thin strip of paper (or a piece of non-stretchy string/floss) about 6 inches long.
2. Wrap it snugly around the base of the finger you'll wear the ring on — snug enough that it doesn't slide, loose enough to still slip over your knuckle.
3. Mark the exact point where the material overlaps with a pen.
4. Lay it flat and measure the length in millimeters with a ruler. That number is your circumference.
5. Match it to the "Inside Circumference" column in the chart above.

Accuracy note: Paper is more reliable than string, because string can stretch slightly under tension while paper holds its length. Either way, this method has roughly ±0.5 size accuracy — good for a first estimate, but confirm with a printed sizer or an in-person measurement before ordering an eternity band, pavé band, or anything else that can't easily be resized later.

Method 2: Measure a Ring You Already Own

If you have a ring that already fits the intended finger well, you can measure it directly instead of your finger:

1. Place the ring on a ruler, or trace its inside edge onto a piece of paper.
2. Measure straight across the inside of the circle, from one inner edge to the opposite inner edge — this is the inside diameter.
3. Match that number to the "Inside Diameter" column in the chart above.

This only works if the reference ring is worn on the same finger and already fits comfortably — a ring sized for a right-hand pinky won't tell you anything useful about a left ring finger.

Method 3: A Printable Ring Sizer

The most accurate at-home option, provided it's printed correctly:

1. Print the sizer PDF at 100% scale — never "fit to page" or "shrink to fit," which will silently resize the guide and throw off every measurement.
2. Confirm the scale by holding a ruler up to the printed calibration line before you rely on it.
3. Cut out the sizer, wrap it around your finger, and read the size where it lines up.

Printing at the wrong scale is the single most common mistake people make with this method — always verify against a ruler first.

Method 4: A Jeweler or Professional Mandrel

The most accurate method of all is a metal ring mandrel or sizing tool used by a jeweler. If you're between two sizes, ordering an expensive eternity band, or sizing for a partner without their knowledge (a common ask before a proposal), it's worth having a professional confirm your at-home measurement before you place a final order. Reach out to our team — we're happy to talk you through it.

Common Mistakes That Throw Off Your Measurement

• Measuring cold fingers. Fingers shrink slightly in cold temperatures and swell in heat and humidity — measure at normal room temperature.
• Measuring first thing in the morning. Fingers are typically at their smallest in the morning and largest by evening. Measure in the late afternoon or evening for the truest everyday fit.
• Pulling the string or paper too tight. This gives you a size that's smaller than what you'll actually need.
• Forgetting the dominant hand runs larger. Most people's dominant hand is about a quarter to a half size bigger than the other. Measure the exact finger on the exact hand you'll wear the ring on.
• Ignoring your knuckle. If your knuckle is noticeably bigger than the base of your finger, a ring sized only to the base will never get past it comfortably. Size for the knuckle and consider a comfort-fit profile (below) so it still slides on smoothly.
• Not accounting for band width. Covered in detail next — this is the mistake most specific to wedding bands, and the one generic ring size guides tend to skip.

Wedding Band Width and Sizing: What Generic Guides Miss

Wedding-Band Specific

Here's the part of ring sizing that matters most for a wedding band and least for something like a thin stacking ring: a wider band fits tighter than a narrow band in the exact same labeled size. A wide band covers more surface area of your finger and has to clear your knuckle across its full width, not just at one thin edge — so the same "size 7" feels noticeably snugger in an 8mm band than in a 2mm band.

Women's wedding bands are most commonly 2mm to 3mm wide; men's are most commonly 6mm to 8mm. That gap is exactly why partners in a his & hers matching set often need to size their same measured circumference differently once width is factored in — don't assume the store size number alone tells the whole story for a wider band.

Comfort Fit vs. Standard Fit

A comfort-fit band has a rounded, domed inside profile instead of a flat one. Because less of the band's interior actually contacts your finger, comfort-fit rings generally wear about a half size larger than a standard flat-interior band in the same labeled size — and they slide over the knuckle more easily, which matters if your knuckle runs larger than the base of your finger. If you're a first-time ring wearer or have a prominent knuckle, our comfort-fit wedding bands are worth a look before you finalize a size.

Sizing Considerations by Band Style

Not every wedding band can be resized the same way after the fact, which makes getting the size right at checkout more important for some styles than others:

• Plain and classic bands in gold or platinum are usually the easiest to resize later, typically within about one size up or down.
• Eternity bands and full pavé bands have diamonds set continuously around the entire circumference, so there's no bare metal left to cut and re-weld — these generally cannot be resized at all, or only with visible disruption to the stone pattern. Measure twice before ordering.
• Engraved bands can usually still be resized, but resizing may shorten or shift the engraved text near the seam — mention any engraving to your jeweler before a resize.
• Hand-braided, Celtic, and heavily carved bands have a repeating pattern that can be harder to resize invisibly — a correct initial measurement matters more here than on a plain band.
• Platinum is denser and more labor-intensive to resize than gold, which can mean a longer turnaround and higher cost for the same adjustment.

See our warranty and return policy pages for the specifics on resizing and exchanges after your order arrives.

Sizing for a Matching His & Hers Set

When you're ordering a matching set, each partner needs their own measurement — don't guess one partner's size off the other's, even if you wear "the same size" in shoes or clothing. A few extra things to keep in mind for couples:

• Measure both ring fingers separately, ideally in the evening when hands are at their largest.
• If one half of the set is a wider men's band and the other a narrower women's band, apply the width adjustment table above to each individually — don't apply a men's-width adjustment to a thin women's band or vice versa.
• If you're sizing a partner secretly ahead of a proposal or surprise, borrowing an existing ring they already wear on that finger (Method 2 above) is usually the most discreet and reliable option.

Average Ring Sizes by Hand

These are population averages, not recommendations — always measure the individual finger the ring will be worn on.

Frequently Asked Questions

Still not sure? Read our wedding band buying guide, compare metals in our metal guide, or contact our wedding band specialists for personal help getting the fit right the first time.