Ring Size Converter

Not sure of your size? Use the on-screen sizer below to measure a ring you already have.

1. Calibrate your screen

Hold any standard card (credit, debit or ID card — they are all 85.6 mm wide) flat against the screen and drag the slider until the outline below exactly matches the card's width. This teaches the tool your device's true pixel size.

2. Match your ring

Place a ring you own flat on the screen and drag the slider until the circle fits snugly inside the ring. The size updates live.

Closest ring size: Use this size

International ring size conversion chart. Your current selection is highlighted.

What a ring size really measures

Every ring size ultimately describes the inner diameter (or circumference) of the band. Countries just label that measurement differently, so converting between systems is a matter of looking up the same physical size in each scale.

The sizing systems

• US / Canada use a numeric scale (with half sizes) that increases by about 0.4 mm of diameter per half size.
• UK / Australia / Ireland use an alphabetical scale (A, B, C … Z), where each letter is roughly a third of a US size.
• EU (ISO 8653) states the inner circumference in millimetres directly — an EU 54 ring has a 54 mm circumference.
• Diameter (mm) is the most universal reference: circumference = diameter × π.

How to use this tool

1. Choose the system you already know and select your size — the equivalents appear instantly.
2. Don't know your size? Calibrate the screen with any bank card, then lay a ring on the display and match the circle to its inside.
3. Cross-check against the full chart, which highlights your match.