What is US ring size 7 in EU?

US ring size 7 has an inner diameter of 17.3 mm and a circumference of 54.4 mm. The EU ring size is based on circumference in mm, so US size 7 = EU size 54 (rounded to the nearest whole number). In UK sizing, size 7 corresponds to letter O.

How do I measure my ring size at home?

String method: wrap a thin strip of paper or string around the base of your finger, mark where it overlaps, then measure the length in mm — this is your circumference. Divide by 3.14 to get the diameter. Existing ring method: measure the inner diameter of a ring that fits well using a ruler or calipers. Fingers are typically larger in the evening and in warm weather, so measure at the end of the day for the most accurate reading.

What is UK ring size N in US?

UK ring size N has an inner diameter of approximately 17.0 mm and a circumference of 53.4 mm. This corresponds to US ring size 6.5. UK sizes run in half-letter increments (e.g. N, N½, O), so N½ would fall between US 6.5 and 7.

Ring Size Guide: US, UK, EU Conversion Chart with mm Measurements

Ring Size Conversion Chart (US Sizes 4–13)

Ring sizes use three different systems worldwide. The US and Canada use whole and half numbers (4 through 13). The UK and Australia use letters (F through Z+6). European and Asian countries use the inner circumference in millimeters. The table below covers the most common sizes.

US / Canada	Inner Diameter (mm)	Circumference (mm)	UK / AU	EU / Asia
4	14.9	46.8	H½	47
4½	15.3	48.0	I½	48
5	15.7	49.3	J½	49
5½	16.1	50.6	K½	51
6	16.5	51.9	L½	52
6½	16.9	53.1	N	53
7	17.3	54.4	O	54
7½	17.7	55.7	P	56
8	18.2	57.2	Q	57
8½	18.6	58.5	R	58
9	19.0	59.7	S	60
9½	19.4	61.0	T	61
10	19.8	62.2	U	62
10½	20.2	63.5	V	63
11	20.6	64.8	W	65
12	21.4	67.3	Y	67
13	22.2	69.7	Z+1	70

How to Measure Your Ring Size at Home

Method 1 — String or Paper Strip

Cut a thin strip of paper about 6 inches long and ¼ inch wide.
Wrap it snugly around the base of the finger you want to size. It should be snug but comfortable enough to slide over the knuckle.
Mark where the paper overlaps with a pen.
Lay the paper flat and measure the length to your mark in millimeters. This is your finger's circumference.
Find that circumference in the EU column above to get your ring size in any system.

Method 2 — Existing Ring

Find a ring that fits well on the target finger.
Measure the inner diameter (the inside opening) with a ruler or calipers in millimeters.
Find that diameter in the table above to identify your size.

Tips for Accurate Sizing

Measure in the evening — fingers swell during the day and in warm weather.
Avoid measuring when hands are cold or hot; aim for a comfortable room temperature.
If between two sizes, choose the larger size for comfort.
Wider bands (over 6 mm) fit more snugly than narrow bands, so consider sizing up half a size for wide rings.
Measure the specific finger on the specific hand you intend to wear the ring — the dominant hand is often slightly larger.

Use our length converter to convert ring measurements between millimeters, centimeters, and inches.