🌍 Ring Size Conversion Calculator
📏 About this tool: Our advanced ring size conversion calculator instantly converts between 10+ international ring size standards: USA/Canada, UK/Australia, Europe (ISO), Japan, China, Switzerland, India, and ISO diameter (mm). Based on official circumference/diameter correlations. Perfect for jewelers, shoppers, and global ring sizing — get precise equivalent sizes, view interactive graph, and detailed reference table.
✨ Convert any size
🇺🇸 USA/Canada:—
🇬🇧 UK/Australia:—
🇪🇺 Europe (mm circ):—
🇯🇵 Japan:—
🇨🇳 China (CN):—
🇨🇭 Swiss:—
🇮🇳 India (inner Ø mm):—
📐 Inner Circumference (mm):—
📏 Inner Diameter (mm):—
* Conversion based on international ring size charts (ASTM/ISO). USA numeric (0-16+), UK letters A-Z, EU circumference mm.
📊 Global size correlation (circumference mm)
Graph shows circumference range vs USA size (reference mapping)
📖 International ring size standards reference
| USA/Can | UK/Aus | EU (mm circ) | JP | CN | India (Ø mm) |
|---|
⚡ Advanced mapping: circumference-based linear interpolation for unmatched sizes. Every country standard uses official formulas: USA = (circ_mm – 37.8) / 1.2 approx. All conversions reference base circumference.