Japan Ring Size to US Ring Size Converter

Welcome to our Japan Ring Size to US Ring Size Converter! This tool bridges two distinct ring sizing systems in Japan and the United States.

Japan’s ring sizes are generally numbered from 1 to 27, including only integers. In contrast, US ring sizes use a scale of numbers and half/quarter sizes. Our converter is here to simplify the variation between these two systems. It is aimed to make your international ring shopping hassle-free and ensure a perfect fit every time.

Japan to US

US to Japan

Japan Ring Size:

US Ring Size:

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The Handbook For The Ring Size Converter

Japan Ring Size to US Ring Size Chart
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Japan Ring Size to US Ring Size Chart

Here is the conversion chart we use in the converter:

Japan Ring Size	US Ring Size	Diameter (mm)	Circumference (mm)
1	1.5 – 1.75	13.0	40.8
2	2 – 2.25	13.3	41.9
3	2.5 – 2.75	13.6	42.9
4	2.75 – 3	14.0	44.0
5	3.25 – 3.5	14.3	45.0
6	3.5 – 3.75	14.6	46.1
7	4 – 4.25	15.0	47.1
8	4.5 – 4.75	15.3	48.2
9	4.75 – 5	15.6	49.2
10	5.25 – 5.5	16.0	50.3
11	5.75 – 6	16.3	51.3
12	6 – 6.25	16.6	52.4
13	6.5 – 6.75	17.0	53.4
14	7 – 7.25	17.3	54.5
15	7.25 – 7.5	17.6	55.5
16	7.75 – 8	18.0	56.6
17	8 – 8.25	18.3	57.6
18	8.5 – 8.75	18.6	58.6
19	9 – 9.25	19.0	59.7
20	9.25 – 9.5	19.3	60.7
21	9.75 – 10	19.6	61.8
22	10.25 – 10.5	20.0	62.8
23	10.5 – 10.75	20.3	63.9
24	11 – 11.25	20.6	64.9
25	11.5 – 11.75	21.0	66.0
26	11.75 – 12	21.3	67.0
27	12.25 – 12.5	21.6	68.0

Friendly Heads-Up

Thank you for using our Japan-to-US ring size converter! While we’ve made every effort to ensure accuracy, please consider the following points for the best experience:

Variations in Sizing: The converter provides a general guide, but different brands may have their own sizing standards. Use this tool as a starting point and consult with individual brands for specific measurements.
Factors Affecting Size: For a more accurate size, measure your finger later in the day because fingers may swell in the morning. Physical activities and alcohol consumption can also temporarily enlarge finger size. It’s advisable to measure when your body is in a neutral state.
Comfort is Key: Ensure the chosen ring size offers a comfortable fit, neither too tight nor too loose.

We hope these additional tips assist you in finding a perfect ring size!