Ring size explained

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

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Measuring tools

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 are tools used to measure the inner size of a ring, and are typically made from plastic, delrin, wood, aluminium, or of multiple materials. Digital ring sticks can be used for highly accurate measurements.

Measurement systems

International standard

ISO 8653:2016 defines standard ring sizes in terms of the inner circumference of the ring measured in millimetres.^[1] ISO sizes are used in Austria, France, Belgium, Scandinavia (Norway,^[2] Sweden, Denmark, Finland, Iceland), and other countries in Continental Europe.^{[3] [4]} This international standard specifies a method to measure the ring-size using a ring stick (also called a mandrel or triblet) with defined characteristics, which is 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 size (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
scope=row	Internal diameter (mm)

Other traditional and regional systems

Other ring size measurement systems are used in areas that do not use ISO 8653:2016.

North America

In the United States, Canada, and Mexico, ring sizes are specified using a numerical scale with steps, where whole sizes differ by of internal diameter, equivalent to of internal circumference. The relationship of this size (

s _{NA} ) to ISO 8653:2016 circumference (C _{ISO} ) is C _{ISO} = 2 . 55 x s _{NA} + 36 . 5 , while the relationship to ISO 8653:2016 diameter (d _{ISO} ) is d _{ISO} = 0 . 8128 x s _{NA} + 11 . 63 .

The Circular of the Bureau of Standards^[5] summarizes the situation with this system: "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.

Ireland, United Kingdom, Australia

In Ireland, the United Kingdom and Australia, ring sizes are specified using an alphabetical scale with half sizes. Originally in 1945, the divisions were based on the ring inside diameter in steps of NaNinches.^[6] However, in 1987 BSI updated the standard to the metric system so that one alphabetical size division equals 1.25 mm of circumferential length. For a baseline, ring size C has a circumference of 40 mm.^[7]

India, Japan, China

In India, Japan and China, ring sizes are specified using a numerical scale with whole sizes that do not have a linear correlation with diameter or circumference.

Germany and Netherlands

Netherlands, Germany, and sometimes Argentina use a standard (referred to as the German System^{[8] [9] [10]}) where ring sizes are defined by the diameter of the ring, measured in mm.^{[11] [12]} This system may also be used at times in Russia. ^[13]

Italy, Spain, Switzerland

In Italy, Spain, and Switzerland, ring sizes are specified as the circumference minus 40 mm: for example, size 10 in this system is equivalent to ISO 8653:2016 size 50.^[14] This may also be referred to as the Swiss Ring Size System. ^[15]

Russia

In Russia, ring sizes are equal to the inner diameter rounded to whole and half numbers, sometimes to quarters, for example diameter 16.92 mm is equal to size 17, 16.1 mm is equal to size 16.

Equivalency table

Ring dimensions in various ring size measurement systems^[16]

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, Netherlands, Switzerland
0.458	0.458inches		NaNinches	0
0.466	0.466inches		NaNinches
0.474	0.474inches		NaNinches		A
0.482	0.482inches		NaNinches
0.49	0.49inches		NaNinches	1	B	1
0.498	0.498inches		NaNinches
0.506	0.506inches		NaNinches		C
0.514	0.514inches		NaNinches				1
0.522	0.522inches		NaNinches	2	D	2	2
0.53	0.53inches		NaNinches
0.538	0.538inches		NaNinches		E	3	3
0.546	0.546inches		NaNinches				4
0.554	0.554inches		NaNinches	3	F	4
0.562	0.562inches		NaNinches			5	5
0.57	0.57inches		NaNinches		G
0.578	0.578inches		NaNinches			6	6
0.586	0.586inches		NaNinches	4	H	7
0.594	0.594inches		NaNinches				7
0.602	0.602inches		NaNinches		I	8	8
0.61	0.61inches		NaNinches		J		9
0.618	0.618inches		NaNinches	5		9
0.626	0.626inches		NaNinches		K		10
0.634	0.634inches		NaNinches			10
0.642	0.642inches		NaNinches		L		11
0.65	0.65inches		NaNinches	6		11	12
0.658	0.658inches		NaNinches		M	12
0.666	0.666inches		NaNinches			13	13
0.674	0.674inches		NaNinches		N
0.682	0.682inches		NaNinches	7		14	14
0.69	0.69inches		NaNinches		O		15
0.698	0.698inches		NaNinches			15
0.706	0.706inches		NaNinches		P		16
0.714	0.714inches		NaNinches	8		16	17
0.722	0.722inches		NaNinches
0.73	0.73inches		NaNinches			17	18
0.738	0.738inches		NaNinches		R		19
0.746	0.746inches		NaNinches	9		18
0.754	0.754inches		NaNinches		S		20
0.762	0.762inches		NaNinches			19	21
0.77	0.77inches		NaNinches		T
0.778	0.778inches		NaNinches	10		20	22
0.786	0.786inches		NaNinches		U	21	23
0.794	0.794inches		NaNinches			22
0.802	0.802inches		NaNinches		V		24
0.81	0.81inches		NaNinches	11		23	25
0.818	0.818inches		NaNinches		W
0.826	0.826inches		NaNinches			24	26
0.834	0.834inches		NaNinches		X
0.842	0.842inches		NaNinches	12		25	27
0.85	0.85inches		NaNinches		Y		28
0.858	0.858inches		NaNinches			26
0.866	0.866inches		NaNinches		Z		29
0.874	0.874inches		NaNinches	13		27	30
0.882	0.882inches		NaNinches		Z1
0.89	0.89inches		NaNinches				31
0.898	0.898inches		NaNinches		Z2		32
0.906	0.906inches		NaNinches	14	Z3
0.914	0.914inches		NaNinches				33
0.922	0.922inches		NaNinches		Z4
0.93	0.93inches		NaNinches				34
0.938	0.938inches		NaNinches	15			35
0.946	0.946inches		NaNinches
0.954	0.954inches		NaNinches				36
0.962	0.962inches		NaNinches
0.97	0.97inches		NaNinches	16			37

Resizing

Most rings can be resized; the method of doing so depends on the complexity of the ring and its material. Rings of soft material may be enlarged using mechanical stretching. For example, the ring may be enlarged using a rolling mill, a steel ring mandrel, or a Schwann Ring Stretcher.^[17]

Adding Material

In some cases, the ring may need to be cut open and material either added or removed before fusing the ring together again. The ring may be slightly heated to reveal any solder line so the jeweler can open the ring on the same seam so as to minimize the total number of solder joins on the ring.^[18]

Sizing beads

Small metal beads called sizing beads can be added to the inner circumference of a ring to:

• Decrease the effective inner diameter of a ring that is too big, to aid in holding the ring in place against the finger
• Counterbalance top-heavy rings
• Keep a ring from spinning for wearers whose knuckles are much larger than their finger base^[19]

Sizing beads are typically made of the same metal as the rest of the ring since it is easier to solder two similar metals.

Notes and References

1. Web site: Jewellery – Ring-sizes – Definition, measurement and designation.
2. Web site: Ring and Bangle Size Charts Norwegian Jewelry - Marketplace and Blog . 2024-04-19 . Norwegian Jewelry . en.
3. Web site: European Ring Size Conversion - Buchkosky Jewelers .
4. Web site: International Ring Size Conversion . 2024-04-19 . Larson Jewelers . en.
5. S.W. Stratton, Director . Jan 24, 1921 . Circular of the Bureau of Standards, No 43., Jewelers' and Silversmiths' Weights and Measures . United States Department of Commerce . 39 .
6. British Standard 1283:1945
7. British Standard 6820:1987
8. Web site: Hahnefeld . Bjoern . February 19, 2021 . ringgroesse . live . https://web.archive.org/web/20210510050645/https://www.goldene-zeiten.info/fileadmin/uploads/ringgroesse-ermitteln.pdf . May 10, 2021 . February 12, 2023 . Goldene Zeiten Juweliere.
9. Web site: European Ring Size Conversion - Buchkosky Jewelers .
10. Web site: International Ring Size Conversion . 2024-04-19 . Larson Jewelers . en.
11. Web site: Determine ring size . 2024-04-19 . Le.Paul Jewelgarden . en.
12. Web site: How to measure your ring size . 2024-04-19 . Taj Amsterdam . en.
13. Web site: European Ring Size Conversion - Buchkosky Jewelers .
14. Web site: Ring size measurement. 21 November 2022. de. Juwelier Limburg.
15. Web site: International Ring Size Conversion . 2024-04-19 . Larson Jewelers . en.
16. News: Convert Your Ring Size to MM : Ring Size Guide. Jewelove. 2016-11-27.
17. https://www.ganoksin.com/article/different-methods-how-to- resize-rings/
18. https://www.ganoksin.com/article/different-methods-how-to-resize-rings/
19. https://serengetiwest.com/do-i-need-ring-sizing-beads/ Do I Need Ring Sizing Beads? | Serengeti West Fine Jewelers