Question 1

How accurate is this online ring size calculator?

Accepted Answer

Our calculator uses industry-standard ring size data from professional jewelers. While it provides excellent estimates, we recommend confirming your size with a professional jeweler before purchasing expensive rings. For the best results, measure 2-3 times and use the average.

Question 2

What is the difference between ring diameter and circumference?

Accepted Answer

Diameter is the straight-line distance across the inside of a ring (from one inner edge to the other). Circumference is the distance around the inside of the ring. They are related by the formula: circumference = diameter × π (3.14159). Both measurements can be used to determine ring size.

Question 3

Does finger shape affect ring size?

Accepted Answer

Yes, finger shape can influence how a ring fits. Oval or tapered fingers may find that a ring slides over the knuckle more easily but feels loose at the base. Wide or flat fingers may need a slightly larger size for comfort. Our calculator accounts for this by letting you specify your finger shape.

Question 4

Should I measure my finger in the morning or evening?

Accepted Answer

Measure in the evening when your fingers are at their largest. Fingers swell throughout the day due to activity and temperature. Avoid measuring when your hands are very cold or very hot, as this can give inaccurate results.

Question 5

How do I convert between US, UK, and EU ring sizes?

Accepted Answer

US sizes use numbers (3-15), UK sizes use letters (A-Z), and EU sizes use the inner circumference in millimeters (44-74). Our calculator automatically converts between all major international systems. You can also use our conversion table below for quick reference.

Question 6

What if my ring size falls between two sizes?

Accepted Answer

If you are between sizes, choose the larger size for a more comfortable fit. This is especially important for wider bands (6mm or more), which tend to fit more snugly than thinner bands. You can always have a ring resized by a professional jeweler.

US / CanadaUS	UK / AustraliaUK	EuropeEU	JapanJP	SwitzerlandCH	Diameter (mm)Dia.	Circumference (mm)Circ.
3	F	44	4	4	14 mm	44 mm
3.25	F½	44.6	5	4.5	14.2 mm	44.6 mm
3.5	G	45.2	5	5.25	14.4 mm	45.2 mm
3.75	G½	45.8	6	5.75	14.6 mm	45.8 mm
4	H	46.5	7	6.5	14.8 mm	46.5 mm
4.25	H½	47.1	7	7	15 mm	47.1 mm
4.5	I	47.7	8	7.75	15.2 mm	47.7 mm
4.75	I½	48.3	8	8.25	15.4 mm	48.3 mm
5	J	49	9	9	15.6 mm	49 mm
5.25	J½	49.6	10	9.5	15.8 mm	49.6 mm
5.5	K	50.2	10	10.25	16 mm	50.2 mm
5.75	K½	50.8	11	10.75	16.2 mm	50.8 mm
6	L	51.5	12	11.5	16.5 mm	51.5 mm
6.25	L½	52.1	12	12	16.7 mm	52.1 mm
6.5	M	52.7	13	12.75	16.9 mm	52.7 mm
6.75	M½	53.3	13	13.25	17.1 mm	53.3 mm
7	N	54	14	14	17.3 mm	54 mm
7.25	N½	54.6	14	14.5	17.5 mm	54.6 mm
7.5	O	55.2	15	15.25	17.7 mm	55.2 mm
7.75	O½	55.8	15	15.75	17.9 mm	55.8 mm
8	P	56.5	16	16.5	18.1 mm	56.5 mm
8.25	P½	57.1	17	17	18.3 mm	57.1 mm
8.5	Q	57.7	17	17.75	18.5 mm	57.7 mm
8.75	Q½	58.3	18	18.25	18.7 mm	58.3 mm
9	R	59	19	19	18.9 mm	59 mm
9.25	R½	59.6	19	19.5	19.1 mm	59.6 mm
9.5	S	60.2	20	20.25	19.2 mm	60.2 mm
9.75	S½	60.8	21	20.75	19.4 mm	60.8 mm
10	T	61.5	22	21.5	19.6 mm	61.5 mm
10.25	T½	62.1	22	22	19.8 mm	62.1 mm
10.5	U	62.7	23	22.75	20 mm	62.7 mm
10.75	U½	63.3	23	23.25	20.2 mm	63.3 mm
11	V	64	24	24	20.4 mm	64 mm
11.25	V½	64.6	24	24.5	20.6 mm	64.6 mm
11.5	W	65.2	25	25.25	20.8 mm	65.2 mm
11.75	W½	65.8	26	25.75	21 mm	65.8 mm
12	X	66.5	27	26.5	21.2 mm	66.5 mm
12.5	Y	67.7	28	27.75	21.6 mm	67.7 mm
13	Z	69	29	29	22 mm	69 mm
13.5	Z+1	70.2	30	30.25	22.3 mm	70.2 mm
14	Z+2	71.5	31	31.5	22.6 mm	71.5 mm
14.5	Z+3	72.7	32	32.75	23 mm	72.7 mm
15	Z+4	74	33	34	23.4 mm	74 mm

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