Free Inches to Ring Size Converter

What This Free Ring Size Calculator Offers

This free ring size calculator converts inch-based measurements into the equivalent ring sizes used globally. Acting as both a finger ring size converter and an inch to ring size reference, it eliminates guesswork when shopping for rings from different countries. You simply provide your finger circumference or the inner diameter of an existing ring (in inches), and the tool returns the matching sizes for US/Canada, UK/Australia, France, Germany, Japan, and Switzerland systems. This makes it an ideal tool for anyone needing an International Ring Size Conversion without manual chart lookups.

How to Measure Your Ring Size at Home

Accurate measurement is the first step to a perfect fit. Two reliable methods are described below.

Method 1 – Using a Ring Mandrel
If you have a ring mandrel, simply slide an existing ring onto the tapered rod and note the size indicated at the point where the ring stops. This gives the ring size directly.

Method 2 – Paper or String Method
When no mandrel is available, follow these steps:

1. Cut a thin strip of paper (or use a non-stretch string).
2. Wrap it snugly around the base of the finger you wish to size.
3. Mark the spot where the two ends meet.
4. Lay the strip flat and measure the distance from the start to the mark with a ruler; that distance is the circumference of your finger.
5. To obtain the inner diameter, divide the circumference by $\pi$ (≈ 3.1416):

$$\text{Inner Diameter (in)} = \frac{\text{Circumference (in)}}{\pi}$$

Both the circumference and the diameter can be entered into the finger ring size converter to find the right size.

Inches to Ring Size Conversion Table

The following table provides a cross-reference between inch measurements (inner diameter and circumference) and common ring size systems. This Ring Size Chart in inches allows you to quickly check your measurement against international standards.

Inner Diameter (in)	Circumference (in)	UK / AU	US / CA	France	Germany	Japan	Switzerland
0.39016	1.2257	-	0000	-	-	-	-
0.42205	1.3259	-	00	-	-	-	-
0.45394	1.4261	-	0	-	-	-	-
0.47047	1.4780	A 1/2	-	-	-	-	-
0.48701	1.5300	B	1	-	-	1	-
0.50315	1.5807	C	1 1/2	-	-	-	-
0.52008	1.6339	D	2	41 1/2	13 1/2	2	1 1/2
0.53583	1.6833	E	2 1/2	42 3/4	13 3/4	3	2 3/4
0.55315	1.7378	F	3	44	14	4	-
0.56535	1.7761	G	3 3/8	45 1/4	-	5	5 1/4
0.56890	1.7872	G 1/4	3 1/2	-	-	14 1/2	-
0.57323	1.8008	G 1/2	3 5/8	-	-	6	-
0.57677	1.8120	H	3 3/4	46 1/2	-	-	6 1/2
0.58504	1.8380	H 1/2	4	-	15	7	-
0.59213	1.8602	I	4 1/4	47 3/4	-	-	7 3/4
0.60118	1.8887	I 1/2	4 1/2	-	15 1/4	8	-
0.60630	1.9047	J	4 5/8	49	15 1/2	-	9
0.61811	1.9419	J 1/2	5	-	15 3/4	9	-
0.62205	1.9542	K	5 1/8	50	-	-	10
0.62992	1.9790	K 1/2	5 3/8	-	-	10	-
0.63386	1.9913	L	5 1/2	51 3/4	16	-	11 3/4
0.64173	2.0161	L 1/4	5 3/4	-	-	-	-
0.64606	2.0297	L 1/2	5 7/8	-	-	-	-
0.65000	2.0420	M	6	52 3/4	16 1/2	12	12 3/4
0.66614	2.0927	N	6 1/2	54	17	13	14
0.68307	2.1459	O	7	55 1/4	17 1/4	14	15 1/4
0.69882	2.1954	P	7 1/2	56 1/2	17 3/4	15	16 1/2
0.71614	2.2498	Q	8	57 3/4	18	16	17 3/4
0.72953	2.2919	Q 3/4	8 1/2	-	18 1/2	17	-
0.73268	2.3018	R	8 5/8	59	-	-	19
0.74370	2.3364	R 3/4	9	-	19	18	-
0.75197	2.3624	S	9 1/8	60 1/4	-	-	20 1/4
0.76024	2.3884	S 1/2	9 3/8	-	-	-	-
0.76811	2.4131	T	9 5/8	61 1/2	-	-	21 1/2
0.78110	2.4539	T 1/2	10	-	20	-	-
0.78819	2.4762	U	10 1/4	62 3/4	-	21	22 3/4
0.79528	2.4984	U 1/2	10 1/2	-	20 1/4	22	-
0.80000	2.5133	V	10 5/8	63	-	-	23 3/4
0.81417	2.5578	V 1/2	11	-	20 3/4	23	-
0.81732	2.5677	W	11 1/8	65	-	-	25
0.82992	2.6073	W 3/4	11 1/2	-	21	24	-
0.84606	2.6580	Y	12	67 1/2	21 1/4	25	27 1/2
0.86181	2.7075	Z	12 1/2	68 3/4	21 3/4	26	28 3/4
0.87913	2.7619	Z+1	13	-	22	27	-
0.90787	2.8522	Z+3	-	-	-	-	-
0.93976	2.9524	Z+5	-	-	-	-	-
0.95551	3.0018	Z+6	-	-	-	-	-

How to Use the Converter

Using this free ring size calculator is straightforward:

1. Take your measurement – measure either the inner diameter of a ring that fits you well or the circumference of your finger (using the paper/string method described above).
2. Enter the value in inches – in the calculator fields, specify whether you are entering diameter or circumference.
3. Select the sizing system (optional) – if you already know a ring size in one system, you can use the reverse lookup feature. Choose the system (e.g., US & Canada) and the size to see its diameter, circumference, and equivalents in other scales.
4. Get your size – the converter instantly displays the corresponding ring sizes across all major standards.

Example: Suppose you measured a finger circumference of 2.5 inches. Enter this value into the circumference field. The tool will show that 2.5 inches corresponds to US size 10 5/8, UK/AU size V, French size 63, German size 20 3/4, Japanese size 23, and Swiss size 23 3/4. (You can verify these values in the table above.)

This bidirectional functionality makes the tool equally useful for international purchases and for resizing existing rings.

Practical Tips for Accurate Sizing

To ensure the best fit, keep these points in mind when measuring:

• Measure at the end of the day when fingers are naturally larger.
• Make sure the paper or string slides over the knuckle; if not, size up.
• Consider the width of the ring – wider bands often require a slightly larger size.
• If you fall between sizes, it is usually better to choose the larger size for comfort.