File & Format Converters · Free tool

Ring Size Converter US UK EU JP mm

Ring size US, UK, EU, Japan, plus circumference in mm. Home measurement tips included.

Updated April 2026

Input typeSource countrySize

Your ring size

Circumference

17.35 mm

Inner diameter

5.52 mm

How to measure at home

Wrap a thin strip of paper or string around the base of your finger.
Mark where it overlaps, then measure the length in millimeters — that’s your circumference.
Measure at the end of the day when fingers are largest; avoid right after exercise.
If you’re between sizes, round up — knuckles need room to pass through.
Wider bands (>6mm) fit tighter — go up a half size.

US	UK	EU	JP	mm
3	F	44	4	14.05
3.5	G	45	6	14.46
4	H	46	7	14.86
4.5	I	47	8	15.27
5	J	49	9	15.70
5.5	K	50	10	16.10
6	L	51	11	16.51
6.5	M	52	12	16.92
7	N	54	13	17.35
7.5	O	55	14	17.75
8	P	57	16	18.19
8.5	Q	58	17	18.53
9	R	59	18	18.89
9.5	S	61	19	19.41
10	T	62	20	19.84
10.5	U	63	22	20.20
11	V	64	23	20.68
11.5	W	66	24	21.08
12	X	67	25	21.49
12.5	Y	68	26	21.89
13	Z	70	27	22.33

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What it does

US 7 = UK N = EU 54 = JP 14 = 54.4mm circumference. Five systems plus a string-and-ruler home-measurement guide.

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Enter size or circumference.
Pick source country.
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