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Ring Size Tools

Ring fit reference

Ring Size Converter

Convert common ring sizes across US, UK, Europe, Japan, inside circumference, and inside diameter. Start with the size you already know, then check the closest equivalent before you buy.

Ring Size Conversion Tool

Choose the measurement system you know and the tool will return the matching values for the other common ring size systems.

Open size chart
Known value

Millimeter inputs return the closest common reference size from the chart below.

Current result

Select a size to begin

Converted values will appear here.

US / Canada-
UK / Australia-
Europe / ISO-
Japan-
Inside circumference-
Inside diameter-

Fit reminder

Band width, temperature, hand dominance, and the seller's own sizing pattern can change how a ring feels in real life.

Step by step

How to measure your ring size

  1. Use a thin strip of paper, string, or a flexible measuring tape.
  2. Wrap it around the base of the finger where the ring will sit.
  3. Mark the overlap point carefully.
  4. Measure that length with a metric ruler in millimeters.
  5. Select Inside circumference (mm) in the converter and enter your value.
  6. Compare the result with the chart and, if possible, confirm with the seller before ordering.

Wide bands often feel tighter than thin bands. If you are buying a wide ring, use the chart as a starting point and re-check the seller's fit notes.

Common sizes

Ring Size Conversion Table

Open the full chart page
US / Canada UK / Australia Europe / ISO Japan Circumference (mm) Diameter (mm)

This table covers common reference sizes used in the converter. Sellers may still size rings differently, especially for specialty bands.

Common questions

Ring size FAQ

Are ring sizes the same in every country?

No. The label changes by region, which is why conversion tools are useful. The physical fit can also vary a little by maker.

Is circumference more reliable than guessing a local size?

Usually yes. If you can measure the inside circumference or diameter carefully in millimeters, you can work back to the closest common size with fewer assumptions.

Why can the same size feel different across brands?

Band width, ring profile, inside comfort shape, and seller tolerances can all change how the same labeled size feels on your finger.

Should I size up for wide bands?

Often yes, or at least double-check. Wide bands cover more skin and can feel tighter even when the labeled size matches a thinner band.

Related tools

Keep sizing in one place

MM to Inches Converter Quick size checks for jewelry measurements and product specs. Bracelet Size Guide Use a simple wrist measurement method before ordering cuffs or chains. Necklace Length Guide Compare common necklace lengths and how they sit on the body. Measuring Guide Read the step-by-step method again with extra fit warnings.