Ring Size Guide: US Sizes in mm and Inches, Up to Size 16

You wrap a strip of paper round your finger, read 74 mm off the ruler, and the chart on the shop page stops at 13.5 or a UK Z. Ordering up from a ring that almost fits gives a band that sticks at the knuckle or spins once past it, and tungsten, for one, cannot be resized afterwards. Below is a US ring size chart in millimetres and inches that runs to size 16, three ways to measure at home with how far each can drift, and what to do about a wide knuckle.

The whole sizes below are from Larson Jewelers’ US ring size chart, which lists every quarter size from 3 to 16.

The short answer

Circumference (mm)	Circumference (in)	US size
49.3	1.94	5
51.8	2.04	6
54.3	2.14	7
56.9	2.24	8
59.4	2.34	9
62.2	2.44	10
64.7	2.54	11
67.2	2.65	12
69.7	2.75	13
72.3	2.85	14
74.8	2.95	15
77.3	3.05	16

How to measure your finger at home

Measure the finger the ring is for, late in the day when your hands are warm: fingers are smaller in the early morning and when cold, and Catbird’s sizing guide says to measure three to four times.

A paper strip. Catbird’s method, and Larson and Blue Nile list paper too.

1. Cut a thin strip of paper and wrap it snugly round the base of the finger.
2. Mark the point where it overlaps.
3. Lay it flat and read the millimetre side of a ruler. That is your circumference.

String or floss. Larson’s guide lists both, and Blue Nile’s uses string. Catbird warns against it: “Strings tend to stretch, which can result in a wrong size.” If you use string, keep the tension light and repeat.

A ring that already fits. Measure straight across the inside of the band and match it to a diameter column. Catbird suggests “a plain, narrow band”, since extra wide bands tend to fit slightly small and a large stone can lift the shank.

How far off each method can be

On Larson’s chart, from US 10 to 16, each half size adds 1.2 to 1.3 mm of circumference but only 0.4 mm of diameter (our arithmetic). So:

• A paper strip misread by 1 mm puts you less than half a size out.
• A ring’s diameter misread by 1 mm puts you about 1¼ sizes out, because a whole size is 0.8 mm of diameter in that range. Prefer the strip.
• Inches are coarse. A 1/16-inch ruler mark is about 1.6 mm (our arithmetic), more than a half size. Read millimetres.
• Cold fingers. Beaverbrooks’ guide says your fingers “will be half a size smaller” when you are cold, and Missoma’s that they “can shrink down by half a size” in colder weather.
• Different jewellers. Most jewellers follow the same US chart, Larson says, but results can differ, “often just a half-size”, from how the finger is measured or rounding in tools.

US ring size chart in mm and inches, sizes 10 to 16

This is where three of the four jewellers’ charts used here run out. Blue Nile’s printable chart has circles for sizes 4 to 13.5, and the Beaverbrooks and Missoma charts end at a UK Z, a US 12½ on Larson’s conversion chart. Larson’s US chart carries on to 16; its columns are headed Diameter and Circumference, and its instructions measure a ring’s “diameter or inner circumference”. Blue Nile’s page says its numbers “reflect the inside diameter”, and in all 20 sizes both charts print, the diameters match.

US size	Diameter (mm), Larson	Circumference (mm), Larson	Diameter (in), Larson	Circumference (in), Larson	Inside diameter (mm), Blue Nile
10	19.8	62.2	0.78	2.44	19.8
10½	20.2	63.5	0.79	2.49	20.2
11	20.6	64.7	0.81	2.54	20.6
11½	21.0	66.0	0.83	2.59	21.0
12	21.4	67.2	0.84	2.65	21.4
12½	21.8	68.5	0.86	2.70	21.8
13	22.2	69.7	0.87	2.75	22.2
13½	22.6	71.0	0.89	2.80	22.6
14	23.0	72.3	0.91	2.85	Not on chart
14½	23.4	73.5	0.92	2.90	Not on chart
15	23.8	74.8	0.94	2.95	Not on chart
15½	24.2	76.0	0.95	3.00	Not on chart
16	24.6	77.3	0.97	3.05	Not on chart

Larson also prints the quarter sizes, 0.6 or 0.7 mm of circumference apart in this range. Beaverbrooks’ FAQ says ring sizes “are exactly the same for men and women”, and none of the charts used here splits them.

Sizing over a larger knuckle

If your knuckle is wider than the base of your finger, measure both. Two jewellers give different rules:

• Blue Nile: “If your knuckle is wider than the base of your finger, measure both and choose a size in between for the best fit.”
• Catbird: “If your knuckle is larger than the base of your finger, you may need to go up a half size.”

A worked example on Larson’s chart (our arithmetic): base 64.7 mm, a US 11; knuckle 68.5 mm, a 12½. Blue Nile’s rule points to around an 11¾ (66.6 mm); Catbird’s, counting the half size from the base (our reading), to an 11½. The target, in Catbird’s words, is “snug enough so that it will not fall off, but loose enough to slide over your knuckle with some resistance.”

Two things move the answer:

• Comfort fit. A comfort-fit band is domed on the inside, and Larson’s comfort-fit page says it “slides over the knuckle easier”. It suggests ordering half a size below a standard-fit size measured at a jeweller, except for bands over 8 mm, or the exact size if you used its own sizer.
• Band width. Wide bands fit tighter. Catbird and Blue Nile suggest half a size up for a wide band, Larson suggests considering half a size up past 8 mm, and Beaverbrooks says “you may need to go up a size”.

UK and European ring sizes

Larson’s conversion page describes the European number as inside circumference in millimetres: “a size 40 would mean the inside circumference of a ring is also 40 mm.” So your strip reading is close to your European size. Past Z, its chart runs Z+1 to Z+7. Larson’s columns are transcribed from its chart image; Missoma’s were read on its UK site. Larson says its conversion “takes comfort fit sizing into account”, which may explain part of the gap to Missoma (our reading).

US size	UK, Larson	European, Larson	UK, Missoma	EU, Missoma
9	S	59.5	S	60.25
9½	T	61.0	T	62.75
10	U	62.0	U	63
10½	V	63.5	V	64
11	W	64.5	W	65
11½	X	66.0	X	66.5
12	Y	67.5	Y	67.5
12½	Z	68.5	Z	69
13	Z+1	70.0	Not on chart	Not on chart
14	Z+3	72.0	Not on chart	Not on chart
15	Z+5	74.5	Not on chart	Not on chart
16	Z+7	77.0	Not on chart	Not on chart

The letters match in all eight shared rows; the European numbers do not. Missoma’s are 0.5 to 1.75 higher in seven rows and equal at a 12 (our arithmetic), so a European 63 is a US 10 at Missoma and a 10¼ on Larson’s chart. Beaverbrooks prints millimetres for each UK letter: from S to Y they run 0.5 to 0.8 mm above Larson’s circumference for the matching US size, and at Z both charts print 68.5 mm (our arithmetic). At a European or British shop, compare your millimetres with its own chart. UK clothing labels follow a separate rule, in uk size 6 to us.

Average ring size for men and women

Averages help only when buying a surprise. Catbird’s most commonly purchased women’s sizes are 5 to 7, with 6 the most popular, and men’s 8 to 10½, with 9 the most popular; Blue Nile’s guide lists the same most-purchased ranges and most popular sizes. Beaverbrooks gives the UK average as O for women and T for men, a US 7 and 9½ on Larson’s chart. These are shoppers’ sizes, not a ceiling: a 66 mm strip is an 11½ whatever the average.

How to use the chart with your numbers

• On a row: order that size.
• Between two rows: take the larger. Catbird, Missoma and Blue Nile each say so; Beaverbrooks says it is “usually best to size up slightly”.
• Knuckle well above the base: use the knuckle rules above, or a comfort fit.
• Wide band: add the half size for width after settling the knuckle.
• Over 77.3 mm: Larson’s chart ends at 16. Ask the jeweller for the ring’s inside circumference.

Before you order

• Check the ring is made in your size. A chart row is not a ring in stock; look at the listing’s size menu.
• Check whether it can be resized. Blue Nile lists tungsten, silver and eternity rings with a set number of stones per finger size among rings it cannot resize; Catbird says rings with stones or patterns all the way round usually cannot be.
• Read the returns page before you pay.
• More measuring walkthroughs are in size guides.

Where these numbers come from

Sizes, millimetres and inches are copied from Larson Jewelers’ US and international charts, Blue Nile’s printable chart (both images transcribed), and the Missoma and Beaverbrooks charts; fitting advice is from those pages and Catbird’s guide, all read on 1 October 2026. Step sizes, differences and the knuckle example are our arithmetic.

Frequently asked questions

What is the average ring size for a man?

Catbird's and Blue Nile's guides both put the most purchased men's sizes at 8 to 10½, with a 9 the most popular, and Blue Nile lists its average men's range as 6 to 13. Beaverbrooks gives a UK T as the average for men, which Larson's conversion chart lists as a US 9½. If you measure larger, order your measurement, not the average.

How do I convert a European ring size to US?

Larson's conversion page describes the European number as the inside circumference in millimetres, so find that number in the circumference column of a US chart. On Larson's chart a European 62.0 is a US 10 and 77.0 is a 16. Missoma's chart prints a US 10 as EU 63, so a ring from a European shop is safest bought on its own millimetre figure. Larson notes its conversion "takes comfort fit sizing into account".

What ring size is 2.5 inches around?

On Larson's chart, 2.49 inches of circumference is a US 10½ and 2.52 inches is a 10¾, so 2.5 inches falls between them. Catbird, Missoma and Blue Nile all say to take the larger size when you fall between two.

Should I size up for big knuckles?

Measure the base of the finger and the knuckle. Blue Nile's guide says to choose a size between the two measurements; Catbird's says you may need to go up a half size. A comfort-fit band, domed on the inside, is described by Larson as sliding over the knuckle more easily.