US ring size to EU ring size
The EU size is the ring inner circumference in millimeters, common in Europe and many Gulf jewellers.
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How to use it
- Enter us size.
- 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
Circumference (mm) = π × 25.4 × (0.458 + 0.032 × US size); the EU size is that circumference rounded to a whole number.
Example
Inputs: US size = 7. Result: EU size (ISO): 54; Inner circumference: 54.42 mm; Inner diameter: 17.32 mm.
Limits and caveats
- Sizes are rounded to the nearest step of each system, and shop mandrels can differ slightly.
- Some shops use half EU sizes, so check the exact circumference.
Questions about this tool
What is US 7 in EU ring sizes?
Its circumference is about 54.4 mm, so EU size 54.
What is ISO 8653?
An international standard that defines ring size as the inner circumference in mm, so size 52 is 52 mm around.
How many millimeters between two US sizes?
Each whole US size adds about 2.55 mm of circumference and 0.8128 mm of diameter.