US to Japan Ring Size

Enter a US size to find its Japanese size number, or scan the comparison chart below — perfect for Japanese jewelry, anime rings, and bridal shopping.

Need to convert in reverse? Go to Japan to US Ring Size Converter →

Common US to Japan equivalents

These examples share the same inner diameter. Use the calculator for another size or an in-between measurement.

US 5 corresponds to Japan 9 at 15.7 mm.
US 7 corresponds to Japan 14 at 17.32 mm.
US 9 corresponds to Japan 18 at 18.95 mm.

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Numeric size (e.g. 8) for US/Canada, EU, or Japan — or a letter size (e.g. P 1/2) for UK/Australia.

Converting US sizes to Japanese ring sizes (号 - Go)

Japanese ring sizes are designated by numbers called "Gō" (号). While both the US and Japan use numbers, the scales are distinct: Japanese size 1 starts at 13.0 mm diameter, and each full size increments diameter by approximately 1/3 mm. A US size 6 corresponds to Japanese size 11 (16.4 mm), US size 7 corresponds to Japanese size 13–14 (17.1 mm), and US size 8 corresponds to Japanese size 16 (18.0 mm).

US to Japan reference table

US to Japan ring size conversion
US / CanadaUS, CA, MX	JapanJP, CN, KR, HK, SG	Diameter (mm)
US / CanadaUS, CA, MX3	JapanJP, CN, KR, HK, SG4	Diameter (mm)14.07
US / CanadaUS, CA, MX3.5	JapanJP, CN, KR, HK, SG6	Diameter (mm)14.48
US / CanadaUS, CA, MX4	JapanJP, CN, KR, HK, SG7	Diameter (mm)14.88
US / CanadaUS, CA, MX4.5	JapanJP, CN, KR, HK, SG8	Diameter (mm)15.29
US / CanadaUS, CA, MX5	JapanJP, CN, KR, HK, SG9	Diameter (mm)15.7
US / CanadaUS, CA, MX5.5	JapanJP, CN, KR, HK, SG10	Diameter (mm)16.1
US / CanadaUS, CA, MX6	JapanJP, CN, KR, HK, SG11	Diameter (mm)16.51
US / CanadaUS, CA, MX6.5	JapanJP, CN, KR, HK, SG13	Diameter (mm)16.92
US / CanadaUS, CA, MX7	JapanJP, CN, KR, HK, SG14	Diameter (mm)17.32
US / CanadaUS, CA, MX7.5	JapanJP, CN, KR, HK, SG15	Diameter (mm)17.73
US / CanadaUS, CA, MX8	JapanJP, CN, KR, HK, SG16	Diameter (mm)18.14
US / CanadaUS, CA, MX8.5	JapanJP, CN, KR, HK, SG17	Diameter (mm)18.54
US / CanadaUS, CA, MX9	JapanJP, CN, KR, HK, SG18	Diameter (mm)18.95
US / CanadaUS, CA, MX9.5	JapanJP, CN, KR, HK, SG19	Diameter (mm)19.35
US / CanadaUS, CA, MX10	JapanJP, CN, KR, HK, SG20	Diameter (mm)19.76
US / CanadaUS, CA, MX10.5	JapanJP, CN, KR, HK, SG22	Diameter (mm)20.17
US / CanadaUS, CA, MX11	JapanJP, CN, KR, HK, SG23	Diameter (mm)20.57
US / CanadaUS, CA, MX11.5	JapanJP, CN, KR, HK, SG24	Diameter (mm)20.98
US / CanadaUS, CA, MX12	JapanJP, CN, KR, HK, SG25	Diameter (mm)21.39
US / CanadaUS, CA, MX12.5	JapanJP, CN, KR, HK, SG26	Diameter (mm)21.79
US / CanadaUS, CA, MX13	JapanJP, CN, KR, HK, SG27	Diameter (mm)22.2