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RingSizeConvert.com

US to UK Ring Size

Enter a US/Canada size below to get its UK/Australia equivalent, or scan the full reference table.

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

Common US to UK equivalents

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

  • US 5 corresponds to UK J½ at 15.7 mm.
  • US 7 corresponds to UK N½ at 17.32 mm.
  • US 9 corresponds to UK R½ at 18.95 mm.
How would you like to find your size?

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

Why US and UK ring sizes don't line up numerically

US/Canada uses a numeric scale (e.g. 6, 6.5, 7) where each whole-size step is a fixed increase in inner diameter. UK/Australia (also used in Ireland, New Zealand, and South Africa) uses a letter scale (e.g. N, N½, O) where each letter step is a fixed increase in inner circumference. Because the two scales are built from different base measurements and different step sizes, there's no simple arithmetic shortcut between them — the reliable way to convert is via the shared millimeter measurement both systems are ultimately anchored to, which is exactly what the table below and the calculator above do.

US to UK reference table

US to UK ring size conversion
US / CanadaUS, CA, MXUK / AustraliaUK, IE, AU, NZ, ZADiameter (mm)
US / CanadaUS, CA, MX3UK / AustraliaUK, IE, AU, NZ, ZAFDiameter (mm)14.07
US / CanadaUS, CA, MX3.5UK / AustraliaUK, IE, AU, NZ, ZAGDiameter (mm)14.48
US / CanadaUS, CA, MX4UK / AustraliaUK, IE, AU, NZ, ZAHDiameter (mm)14.88
US / CanadaUS, CA, MX4.5UK / AustraliaUK, IE, AU, NZ, ZAIDiameter (mm)15.29
US / CanadaUS, CA, MX5UK / AustraliaUK, IE, AU, NZ, ZAJ½Diameter (mm)15.7
US / CanadaUS, CA, MX5.5UK / AustraliaUK, IE, AU, NZ, ZAK½Diameter (mm)16.1
US / CanadaUS, CA, MX6UK / AustraliaUK, IE, AU, NZ, ZAL½Diameter (mm)16.51
US / CanadaUS, CA, MX6.5UK / AustraliaUK, IE, AU, NZ, ZAM½Diameter (mm)16.92
US / CanadaUS, CA, MX7UK / AustraliaUK, IE, AU, NZ, ZAN½Diameter (mm)17.32
US / CanadaUS, CA, MX7.5UK / AustraliaUK, IE, AU, NZ, ZAO½Diameter (mm)17.73
US / CanadaUS, CA, MX8UK / AustraliaUK, IE, AU, NZ, ZAP½Diameter (mm)18.14
US / CanadaUS, CA, MX8.5UK / AustraliaUK, IE, AU, NZ, ZAQ¼Diameter (mm)18.54
US / CanadaUS, CA, MX9UK / AustraliaUK, IE, AU, NZ, ZAR½Diameter (mm)18.95
US / CanadaUS, CA, MX9.5UK / AustraliaUK, IE, AU, NZ, ZAS½Diameter (mm)19.35
US / CanadaUS, CA, MX10UK / AustraliaUK, IE, AU, NZ, ZAT½Diameter (mm)19.76
US / CanadaUS, CA, MX10.5UK / AustraliaUK, IE, AU, NZ, ZAU½Diameter (mm)20.17
US / CanadaUS, CA, MX11UK / AustraliaUK, IE, AU, NZ, ZAV½Diameter (mm)20.57
US / CanadaUS, CA, MX11.5UK / AustraliaUK, IE, AU, NZ, ZAW½Diameter (mm)20.98
US / CanadaUS, CA, MX12UK / AustraliaUK, IE, AU, NZ, ZAX½Diameter (mm)21.39
US / CanadaUS, CA, MX12.5UK / AustraliaUK, IE, AU, NZ, ZAY½Diameter (mm)21.79
US / CanadaUS, CA, MX13UK / AustraliaUK, IE, AU, NZ, ZAZ½Diameter (mm)22.2