Ring Size Converter
Enter a finger measurement or select a US size to see equivalent UK letters, EU circumferences, and millimeter values.
US Size
8
UK equivalent: Q
Metric Dimensions
Diameter: 18.10 mm
Circumference: 56.90 mm
Notes
Matches closely with a standard ring size.
How to Use This Converter
Measure your finger or ring
Wrap a tape around your finger for circumference or measure the inner diameter of a well-fitting ring.
Enter the measurement
Choose the appropriate unit and measurement type, or select a known US ring size from the list.
Review size conversions
Check US, UK, and EU equivalents and note any recommendation about in-between sizes.
Formula & Reference
Circumference = π × Diameter
1 inch = 25.4 mm
Ring sizes follow standardized ISO charts. This converter uses industry-average diameter and circumference values for US sizes 3–13.5.
Example: Circumference 56.5 mm → closest size is US 8 (UK Q), diameter ~18.1 mm.
About the Ring Size Converter
Ring sizing varies between countries. This converter bridges US numeric, UK letter, and metric systems, making it easy to order rings online or translate jeweler charts.
When to Use This Converter
- Online shopping: Convert between international sizing charts before ordering.
- Jewelry making: Translate customer measurements into standardized sizes.
- Gift giving: Match a known ring size from one system to another.
- Travel: Understand sizing differences when buying rings abroad.
Why Use Our Converter?
- ✅ Multiple inputs: Works with circumference, diameter, or US sizes.
- ✅ Accurate chart: Based on widely accepted ISO standards.
- ✅ Helpful notes: Indicates when measurements fall between sizes.
- ✅ Mobile friendly: Ideal for in-store measuring.
Common Applications
Jewelers: Provide quick conversions for customers.
DIY makers: Size rings accurately without complex charts.
Couples: Determine partner sizes for engagement rings or wedding bands.
Tips for Best Results
- Measure fingers at the end of the day when they are largest.
- Consider seasonal changes—fingers swell in heat and shrink in cold.
- If between sizes, size up for comfort or consult a jeweler for resizing options.
- For wide bands, size up ¼–½ size to accommodate tighter fit.
Frequently Asked Questions
How do I measure circumference accurately?
Use a flexible measuring tape or a strip of paper. Mark the overlap, measure the length, and enter it in the converter.
Can I convert to European numeric sizes?
European sizes use circumference in millimeters. The converter shows this value so you can match EU charts directly.
What if my measurement doesn’t match exactly?
The converter finds the closest standard size and highlights if the measurement is between sizes. Jewelers can resize rings for a perfect fit.
Do men and women use different charts?
No. Ring sizes are unisex; the same charts apply to all wearers.