Ring Size Converter

Convert between ring sizes across different regions

Our free online ring size converter supports 5 different units with instant, accurate results. All conversion factors are based on definitions from the International Bureau of Weights and Measures (BIPM) and verified against NIST standards. Results are accurate to 6 or more decimal places.

Download Printable Conversion Table (PDF)

Popular Ring Size Conversions

US/Canada → UK/Australia

US → UK

UK/Australia → US/Canada

UK → US

US/Canada → EU (mm circumference)

US → EU

EU (mm circumference) → US/Canada

EU → US

US/Canada → Diameter (mm)

US → mm

Diameter (mm) → US/Canada

mm → US

UK/Australia → EU (mm circumference)

UK → EU

EU (mm circumference) → UK/Australia

EU → UK

All Ring Size Conversions

Convert Ring Size Units

Convert from US/Canada (US)

→ UK/Australia

→ EU (mm circumference)

→ Japan

→ Diameter (mm)

Convert from UK/Australia (UK)

→ US/Canada

→ EU (mm circumference)

→ Japan

→ Diameter (mm)

Convert from EU (mm circumference) (EU)

→ US/Canada

→ UK/Australia

→ Japan

→ Diameter (mm)

Convert from Japan (JP)

→ US/Canada

→ UK/Australia

→ EU (mm circumference)

→ Diameter (mm)

Convert from Diameter (mm) (mm)

→ US/Canada

→ UK/Australia

→ EU (mm circumference)

→ Japan

Last updated: November 27, 2025