Ring Size Converter
Convert ring sizes between US, UK, European, and millimeter measurement systems with comprehensive half-size support for accurate jewelry fitting
🌈 Browse More Tools
Complete Guide: Ring Size Converter
Everything you need to know about using this tool effectively
The Ring Size Converter translates ring sizes between US numeric sizes, UK letter sizes, EU sizes, and inner circumference in millimeters. Different countries use different sizing systems for rings, and this tool lets you find your size in any system. All processing happens in the browser.
This tool uses lookup tables mapping ring sizes across US, UK, EU, and mm circumference standards. You enter a size in one system and the tool shows the equivalent in all others.
Buying rings from international retailers
Convert your US ring size to UK letter size when ordering from a British jeweler.
Surprise gift shopping
Convert a known ring size to the system used by the store where you are buying.
Measuring ring size at home
Measure the inner circumference in mm and find the corresponding size in any system.
Comparing ring brands
Check if your size translates consistently across different brands' sizing systems.
Enter your size
Type your known ring size and select the system (US, UK, EU, or mm).
View equivalents
The tool shows the matching sizes in all four systems.
Copy the result
Copy the size you need for the retailer.
US sizes are numeric (e.g., 7). UK sizes are letters (e.g., N).
Ring size is based on inner circumference. Measure with a string or paper strip.
Finger size changes with temperature. Measure at room temperature for best accuracy.
If between sizes, go up. A slightly loose ring is more comfortable than a tight one.
What sizing systems are supported?
US (numeric), UK (letter), EU (numeric), and inner circumference in millimeters.
How do I measure my ring size?
Wrap a string or paper strip around your finger, mark where it overlaps, and measure the length in millimeters. Enter that as the circumference to find your size.
Is my data sent to a server?
No. All conversion happens in your browser. Nothing is transmitted.
Do ring sizes vary between brands?
There can be slight variations between manufacturers. The converter uses standard sizing charts, which are accurate for most mainstream jewelers.
Can I convert half sizes?
Yes. The tool supports half sizes in the US system (e.g., 6.5, 7.5).