Convert a ring's measured circumference or diameter into a US ring size.
How It Works
How Ring Size Converter Works
The calculator matches your measurement against the standard reference table jewelers use, mapping circumference in millimeters to US ring sizes, interpolating between listed sizes when your measurement falls between two standard values.
FAQ
Frequently Asked Questions
Should I measure circumference or diameter?
Either works — a string wrapped around the finger and then measured against a ruler gives circumference directly, while measuring an existing ring's inner opening gives diameter; the calculator converts between the two automatically.
How accurate is a self-measurement compared to a jeweler's sizer?
It's a good starting estimate, but finger size can vary slightly with temperature and time of day, and a physical jeweler's ring sizer will always be more precise for a final purchase.
