Ring size

Ring size is a measurement used to denote the circumference (or sometimes the diameter) of jewellery rings and smart rings.

For the "ring gauge" used for cigars (1/64 inch), see Cigar.

Measure

An analogic sizing ring stick

Ring sizes can be measured physically by a paper, plastic or metal ring sizer (as a gauge) or by measuring the inner diameter of a ring that already fits.

Ring sticks used to measure the inner size of a ring can be made from a variety of materials including plastic, delrin, wood, aluminium, aluminium with wooden handle and so on. Digital ring sticks also exist.

ISO sizes

The ISO standard for ring sizes is ISO 8653:2016, which defines standard ring sizes in terms of the inner circumference of the ring measured in millimetres.[1] ISO sizes are used in Austria, France, Germany, Belgium and Scandinavia (Norway, Sweden, Denmark, Finland, Iceland), as well as some other countries in Continental Europe.

This international standard specifies a method to measure the ring-size using a ring stick with defined characteristics, which is mainly used during manufacturing steps, and specifies the designation of the ring-size.

For jeweller-consumer relationships, the finger size is measured with a finger gauge set made up of a ring for each size with the same diameter and tolerance as the ring stick ones. The sizes are in millimeters and correspond directly to the outer circumference of the ring stick to the inner circumference of the finger gauge.

ISO sizes 49 to 72

Internal ring circumference (mm)	49	50	51	52	53	54	55	56	57	58	59	60	61	62	63	64	65	66	67	68	69	70	71	72
Internal diameter (mm)	15.6	15.9	16.2	16.6	16.9	17.2	17.5	17.8	18.1	18.5	18.8	19.1	19.4	19.7	20.1	20.4	20.7	21.0	21.3	21.6	22.0	22.3	22.6	22.9

Other traditional and regional systems

There are several systems for denoting the sizes of jewellery rings in use around the world:

• In the United States, Canada and Mexico ring sizes are specified using a numerical scale, with quarter and half sizes. An increase of a full size is an increase of 0.032 inch (0.8128 mm) in diameter, or roughly 1/10 inch (more precisely, 0.1005 in or 2.55 mm) in inside circumference.
• In Ireland, the United Kingdom and Australia, ring sizes are specified using an alphabetical scale, with half sizes.
• In India, Japan and China, ring sizes are specified using a numerical scale, that only has whole sizes, and does not have simple linear correlation with diameter or circumference.
• In Italy, Spain, Netherlands, and Switzerland, ring sizes are specified as the circumference minus 40 mm. A 50 ISO was a 10 in Switzerland.

For the system prevailing the United States, the Circular of the Bureau of Standards [2] summarizes the situation as: "While there apparently is only one standard in use in the United States, in reality, because of the lack of specific dimensions and because of the errors introduced by the adoption of a common commercial article as a pattern, there are many, although similar, standards." The standards are generally consistent and remain so. There does not appear to have been any improvement in the standard since then.

Chart for size conversions

Conversion chart for ring sizes[3]

Inside diameter		Inside circumference		Sizes
(in)	(mm)	(in)	(mm) ISO (Continental Europe)	United States, Canada and Mexico	United Kingdom, Ireland, Australia, South Africa and New Zealand	East Asia (China, Japan, South Korea), South America	India	Italy, Spain, Switzerland
0.458	11.63	1.44	36.5	0
0.466	11.84	1.46	37.2	¼
0.474	12.04	1.49	37.8	½	A
0.482	12.24	1.51	38.5	¾	A½
0.49	12.45	1.54	39.1	1	B	1
0.498	12.65	1.56	39.7	1¼	B½
0.506	12.85	1.59	40.4	1½	C			0.5
0.514	13.06	1.61	41.0	1¾	C½		1	1
0.522	13.26	1.64	41.7	2	D	2	2	1.75
0.53	13.46	1.67	42.3	2¼	D½			2.25
0.538	13.67	1.69	42.9	2½	E	3	3	3
0.546	13.87	1.72	43.6	2¾	E½		4	3.5
0.554	14.07	1.74	44.2	3	F	4		4.25
0.562	14.27	1.77	44.8	3¼	F½	5	5	4.75
0.57	14.48	1.79	45.5	3½	G			5.5
0.578	14.68	1.82	46.1	3¾	G½	6	6	6
0.586	14.88	1.84	46.8	4	H	7		6.75
0.594	15.09	1.87	47.4	4¼	H½		7	7.5
0.602	15.29	1.89	48.0	4½	I	8	8	8
0.61	15.49	1.92	48.7	4¾	J		9	8.75
0.618	15.70	1.94	49.3	5	J½	9		9.25
0.626	15.90	1.97	50.0	5¼	K		10	10
0.634	16.10	1.99	50.6	5½	K½	10		10.5
0.642	16.31	2.02	51.2	5¾	L		11	11.25
0.65	16.51	2.04	51.9	6	L½	11	12	11.75
0.658	16.71	2.07	52.5	6¼	M	12		12.5
0.666	16.92	2.09	53.1	6½	M½	13	13	13.25
0.674	17.12	2.12	53.8	6¾	N			13.75
0.682	17.32	2.14	54.4	7	N½	14	14	14.5
0.69	17.53	2.17	55.1	7¼	O		15	15
0.698	17.73	2.19	55.7	7½	O½	15		15.75
0.706	17.93	2.22	56.3	7¾	P		16	16.25
0.714	18.14	2.24	57.0	8	P½	16	17	17
0.722	18.34	2.27	57.6	8¼	Q			17.5
0.73	18.54	2.29	58.3	8½	Q½	17	18	18.25
0.738	18.75	2.32	58.9	8¾	R		19	19
0.746	18.95	2.34	59.5	9	R½	18		19.5
0.754	19.15	2.37	60.2	9¼	S		20	20.25
0.762	19.35	2.39	60.8	9½	S½	19	21	20.75
0.77	19.56	2.42	61.4	9¾	T			21.5
0.778	19.76	2.44	62.1	10	T½	20	22	22
0.786	19.96	2.47	62.7	10¼	U	21	23	22.75
0.794	20.17	2.49	63.4	10½	U½	22		23.25
0.802	20.37	2.52	64.0	10¾	V		24	24
0.81	20.57	2.54	64.6	11	V½	23	25	24.75
0.818	20.78	2.57	65.3	11¼	W			25.25
0.826	20.98	2.59	65.9	11½	W½	24	26	26
0.834	21.18	2.62	66.6	11¾	X			26.5
0.842	21.39	2.65	67.2	12	X½	25	27	27.25
0.85	21.59	2.67	67.8	12¼	Y		28	27.75
0.858	21.79	2.70	68.5	12½	Z	26		28.5
0.866	22.00	2.72	69.1	12¾	Z½		29	29
0.874	22.20	2.75	69.7	13		27	30	29.75
0.882	22.40	2.77	70.4	13¼	Z1			30.5
0.89	22.61	2.80	71.0	13½			31	31
0.898	22.81	2.82	71.7	13¾	Z2		32	31.75
0.906	23.01	2.85	72.3	14	Z3			32.25
0.914	23.22	2.87	72.9	14¼			33	33
0.922	23.42	2.90	73.6	14½	Z4			33.5
0.93	23.62	2.92	74.2	14¾			34	34.25
0.938	23.83	2.95	74.8	15			35	34.75
0.946	24.03	2.97	75.5	15¼				35.5
0.954	24.23	3.00	76.1	15½			36	36.25
0.962	24.43	3.02	76.8	15¾				36.75
0.97	24.64	3.05	77.4	16			37	37.5

Equations

To convert from US, Canada and Mexico ring sizes (s) to ISO 8653:2016 circumference:

${\displaystyle c=2.55\times s+36.5}$

and for diameter:

${\displaystyle d=0.8128\times s+11.63}$

Resizing a ring

Most rings can have their size adjusted to some extent. There are various methods which may be suitable depending on the complexity of the ring and material used. For example, rings of soft material may be opened somewhat using a special form of punch. In other cases the ring may need to be cut open and material either added or removed, before fusing the ring together again. All other factors being equal, sizing a ring up will cost more than sizing a ring down; sizing up requires the jeweler add precious metal, sizing down allows them to remove (and re-use) it.

Sizing beads

Sizing beads are an alternative way to reduce the functional ring size by adding small metal beads to the inner surface of a ring, and can aid in holding the ring in place against the finger. Mounting sizing beads can be an easy way to resize a ring that is too big. They are also sometimes used on very top heavy rings as a counter balance. Persons who have knuckles that are much larger than their finger base may also benefit from sizing beads to keep a ring from spinning.[4] Sizing beads are typically made of the same metal as the rest of the ring, since it is easier to solder two similar metals.

References

1. "Jewellery -- Ring-sizes -- Definition, measurement and designation".
2. S.W. Stratton, Director (Jan 24, 1921). Circular of the Bureau of Standards, No 43., Jewelers' and Silversmiths' Weights and Measures (Report). United States Department of Commerce. p. 39.
3. "Convert Your Ring Size to MM : Ring Size Guide". Jewelove. Retrieved 2016-11-27.
4. Do I Need Ring Sizing Beads? | Serengeti West Fine Jewelers