To measure ring size at home, you need a ruler and either a ring that already fits or a strip of paper. Either way it comes down to one number in millimeters: the inside diameter of that ring, or the circumference of the finger the ring will sit on.
Then look at how wide the band is. Our rule: if it's wider than 6mm, order one full size above what you measured, and at 6mm or narrower, order the size you measured.
How We Size a Ring Here
Almost every sized ring we sell is listed in US sizes and stocked size by size, so the size you pick is a finished ring that ships as it is. The few designs that are made to order say so on their page, and adjustable rings, covered below, come as one open band.
We check ring sizes on a ring mandrel, the tapered, marked rod a ring slides down until it stops. The reading is a US size, the only scale our rings are sold in.
On a wide band, we read the size at the center of the band. A mandrel tapers, so a 13mm band spans a stretch of the rod where the diameter keeps changing, and a reading taken at one edge can differ from one taken at the center. GIA's ring-size guide gives the same advice for unusually wide bands: take the measurement from the center.
Measure Your Finger at Home: Two Ways
Measure a ring that already fits
Put a ring that fits the same finger on a ruler and measure straight across the inside, at the widest point. That's the inside diameter: choose “Diameter (mm)” in the converter on our ring size chart and enter it. GIA's jeweler guidance notes that the inside of the ring must be perfectly round for this to work, and GIA's ring-size guide suggests a plain band worn on that same finger.
Or wrap a paper strip around the finger
Cut a thin strip of paper, wrap it once, snugly, around the base of the finger, mark where it overlaps, and measure to the mark in millimeters. That's the finger's circumference, a rough starting estimate rather than a final answer, since GIA notes paper can shrink and curl with humidity and temperature. Then check that the size will still pass over your knuckle, which for most people is wider than the rest of the finger.
Cold fingers throw the reading off too. GIA's ring-size guide notes that fingers shrink in the cold and swell in the heat, and that a cool-morning reading can differ from an afternoon one, so don't measure cold hands. GIA's jeweler guidance is to take a finger size on three different occasions, so if you can, measure on different days and compare.
Skip string, which can stretch. Measure the exact finger, on the exact hand, that the ring is for; if you haven't picked one yet, see which fingers our customers choose. Between two sizes on a band 6mm or narrower, take the larger one.
Wide Band Ring Size: Go Up One Full Size
Width matters on our rings because most of the ones that state a width are wide. A wider band covers more of your finger, so it fits tighter than a slim band with the same inside diameter. GIA's ring-size guide puts it simply: rings with wide shanks usually need to be a bit larger because they fit more snugly.
How much to size up for a wide band ring depends on the band and the hand. GIA's jeweler guidance says a wide ring might need half a size to a full size more than a narrow one, depending on the finger joint and what feels comfortable, and examples of published retailer advice run from a quarter size to a full size.
Our rule: if the band is wider than 6mm, order one full size above what you measured. At 6mm or narrower, order the size you measured.
Add that full size to the reading itself, without rounding up first: a 9¼ reading on a wide band becomes a 10¼, a size nearly all of our sized rings come in.
Nearly every ring in our catalog that states a band width is on the size-up side of that rule. Of the 68 that do, 67 are wider than 6mm, counting each at its widest point. The median is 13mm, and the widest we list is our tribal flame wolf ring at 22mm, with the flame skull crossbones ring close behind at 20mm.
Most listings don't state a band width yet: 68 of our 458 rings do. If the ring you want doesn't, email support@bikerringshop.com before you order and we'll check it for you.
Ring Size Conversion: UK to US and Millimeters
After how to measure, the questions we get most are how to turn a UK letter, or a number in millimeters, into a US size. By GIA's chart, a UK R is a US 9, a UK T is a US 10 and a UK V is a US 11. Here are US 7 to 13 from that chart:
| UK & Australia | US size | Inside diameter (mm) | Inside circumference (mm) |
|---|---|---|---|
| N | 7 | 17.3 | 54.3 |
| P | 8 | 18.1 | 56.9 |
| R | 9 | 19.0 | 59.7 |
| T | 10 | 19.8 | 62.2 |
| V | 11 | 20.6 | 64.7 |
| X | 12 | 21.4 | 67.2 |
| Z½ | 13 | 22.2 | 69.7 |
Source: GIA ring-size chart.
Charts don't agree letter for letter. GIA puts a US 8 at P, while Stuller's 2012 comparison chart lists Q, so when two charts disagree, go by the millimeters. ISO 8653 defines a ring size as the inside circumference in millimeters, so on a chart that follows it, size 62 is about 62mm around: roughly a US 10. For half sizes and anything above 13, use the size converter.
Average Ring Size for Men: What Our Orders Show
If you're buying a ring for someone you can't measure, averages are a last resort. Across 19,135 sized rings ordered from us between December 2017 and October 17, 2026, not counting rings titled as women's or bridal, test orders, canceled orders or refunded units, the median size was US 10.5, and the most-ordered single size was 11. About 35% were size 12 or larger, and roughly eight in ten fell between sizes 7 and 14.
Only ring orders with a US size recorded are counted, and we don't record who wears a ring. Those rings went to buyers in 91 countries, and there's no separate men's scale behind the numbers: a US 10 is the same nominal inside measurement whoever wears it.
Adjustable Rings: Bending the Band to Fit
Some of our rings have an open band you can close or open by hand. The range depends on the design, and each ring's page lists its own: our smaller adjustable rings start as low as US 4.5 to 5.5, and the larger ones go up to US 12. The Norse Viking dragon ring, for example, adjusts from US 7 to 12.
You can bend it again later for a small fit change, within the ring's listed range. Use slow, even pressure and avoid bending the same spot back and forth. Bending sterling silver to change its shape work-hardens it, and too much working can make it crack; the metallurgist Chris Corti explains how bending, hardening and cracking connect in his notes on cracks in jewelry manufacturing. We can't give you an exact number of bends.
If the Size Is Wrong
We don't resize rings once they've been delivered. If a ring doesn't fit, we exchange it for a size we have in stock: email us, send it back unworn within 45 days of delivery, and cover the return postage. We ship the new size to you free, with no exchange fee. The full terms are in our return policy.
If the size you need isn't in stock, email us before you order. Some designs can be adjusted from a nearby size before they ship, by up to two or three sizes depending on the design, and some can't be adjusted at all. The flame skull crossbones ring, for one, can move up to two sizes.
Size exchanges are rare: our order log for December 2025 to October 2026 shows roughly one ring order in a hundred needing a different size.
Found your size? Browse our rings, and remember the rule: wider than 6mm, go up one.