International ring size chart
Choose a US size range and step to build a full comparison chart.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter from us size, to us size and step.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
For each US size: diameter = 25.4 × (0.458 + 0.032 × size) mm, circumference = π × diameter, then mapped to the UK letter, EU, Japanese and Italian numbers.
Example
Inputs: From US size = 3, To US size = 13, Step = Half size. Result: Size chart: ; Rows: 21.
Limits and caveats
- Sizes are rounded to the nearest step of each system, and shop mandrels can differ slightly.
- Japanese numbers follow JCS; Italian numbers are the circumference minus 40.
Questions about this tool
What is the most common size?
Sizes vary a lot between people, so measure your finger rather than rely on an average.
Can I print the chart?
Yes, but rely on the millimeter columns, not on how large the printout comes out.
Why does a cell say outside the chart?
Some systems do not cover very small or large sizes, such as Japanese beyond 30.