RingSizeCalculator

Ring size converter

Convert a size you know between US / Canada, UK / Australia, EU, India, and Japan.

Choose your current ring size

US6EU ≈52
Approximate international equivalents

Regional systems don’t line up exactly. We convert through inner diameter and show the closest supported size in each system.

US half sizes and UK half-letter sizes supported. India uses BlueStone’s numeric convention; Japan uses 4°C’s diameter chart. See sources and supported ranges.

No account or photos needed. Measurements stay in your browser.Measurement guide →
Screen calibration

Calibrate your screen

On a phone, tablet, or computer, matching a bank card is the simplest way to set the scale.

Hold a standard ID-1 bank card upright against the screen. Adjust the outline to match its outside edges: 53.98 mm wide and 85.60 mm tall. Keep browser zoom unchanged.

Tap − or + for small adjustments, or drag the slider. No photos or card details needed.

Match your card53.98 mm ↔

On a short screen, scroll to check the edges. If your card cannot fit across the screen, use paper-strip measurement instead. Never shrink the outline just to make it fit.

Saved only in this browser.

Check the seller’s size chart

International sizing systems do not line up exactly. This converter uses inside diameter to find the closest reference size. A brand’s own sizing chart takes priority, especially for wide bands or smart rings.

Read the ring size conversion guide →