Sunday 1 November 2026

Gold $3,876.40/oz -0.2% Silver $49.25/oz +0.3% Platinum $1,439.00/oz +0.5% Palladium $1,001.00/oz +0.2%

JewelLoop · Ring size converter

https://jewelloop.net/tools/ring-size-converter/

Estimates for guidance; verify before production.

Trade tools · Sizes and conversions

Ring size converter

Convert a ring size between the US, UK, European, Japanese and Swiss systems, or start from a measurement in millimetres.

Full ring size chart

US/CA	UK/AU	EU/ISO	Japan	Swiss	Diameter mm	Circumference mm
3	F½	44	4	4	14.07	44.2
3.5	G½	45	5	5.5	14.48	45.5
4	H½	47	7	7	14.88	46.8
4.5	I½	48	8	8	15.29	48.0
5	J½	49	9	9.5	15.70	49.3
5.5	K½	51	10	10.5	16.10	50.6
6	L½	52	12	12	16.51	51.9
6.5	M½	53	13	13	16.92	53.1
7	N½	54	14	14.5	17.32	54.4
7.5	O½	56	15	15.5	17.73	55.7
8	P½	57	16	17	18.14	57.0
8.5	Q½	58	18	18.5	18.54	58.3
9	R½	60	19	19.5	18.95	59.5
9.5	S½	61	20	21	19.35	60.8
10	T½	62	21	22	19.76	62.1
10.5	U½	63	23	23.5	20.17	63.4
11	V½	65	24	24.5	20.57	64.6
11.5	W½	66	25	26	20.98	65.9
12	Y	67	26	27	21.39	67.2
12.5	Z	68	27	28.5	21.79	68.5
13	Z+1	70	29	29.5	22.20	69.7

Estimates for guidance; verify before production.

Understand the result

Ring sizes: converting US, UK, EU and Japan

How ring sizes work

Every system describes the same thing: the inside of the ring. Europe (ISO 8653) uses the inside circumference in millimetres. The US and Canada use numbers that grow by about 0.81 mm of diameter per size. The UK and Australia use letters, and Japan uses its own numbers.

Measuring at home or at the bench

The most reliable way is a ring sizer or a mandrel. Measuring the inside diameter of a ring that fits well also works. Wide bands fit tighter than narrow ones, so go up about a quarter to half a size for bands over 6 mm.

Sizes differ slightly between makers' mandrels. Confirm the size with your customer before production.

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