This inches to ring size converter turns a ring diameter in inches into sizing information for US, UK, Australian, French, Russian, German, Swiss, and Japanese ring scales.
Everyday life
Inches To Ring Size Converter
Convert ring diameter in inches to US and international ring sizes.
Calculator
About this calculator
Formula notes
Circumference = pi x diameter; ring size tables map measured diameter or circumference to each regional numbering system.
Worked examples
- Example: a 0.7 inch diameter has a circumference of about 2.20 inches and maps to common US ring sizes in the 6-7 range.
- A 0.748 inch inner diameter is close to a US size 7 ring.
How to use it
- Measure the inside diameter of the ring in inches.
- Choose the regional ring scale to convert from.
- Read the equivalent sizes across all supported regions.
Frequently asked questions
Should I measure diameter or circumference?
Either works if you enter the corresponding field. The converter accepts diameter and also calculates the circumference from it.
Are all countries' ring sizes the same?
No. Each regional system uses a different numbering and sizing convention, which is why the result includes multiple scales.
Limits and interpretation
- Ring sizing tables are reference guides; actual fit also depends on ring width, finger shape, and temperature.
- Measuring the inside diameter accurately is important—a small measurement error can shift the size.