Identify the current sizing system first, keep the ring's inside millimeter measurement visible, and use one clearly labeled conversion chart as a reference. Then confirm the target maker's sizing and actual fit instead of treating a cross-system label as exact.

Translate a ring size between named systems without hiding the millimeter measurement, chart source, maker differences, or need for a physical fit check.

What this guide covers

Name the source sizing system
Preserve the millimeter reference
Read one labeled target chart
Confirm the maker and fit

A conversion is a reference, not a fit promise

Conversion boundary
Countries and brands can use different labels, increments, and collection guidance. Keep the original system and inside millimeter reference beside the converted label, then verify the intended maker before ordering.

What you need before converting

If one of these details is missing, pause rather than guessing which column applies.

The named source system

Record whether the original label belongs to a US, UK, European, Japanese, or another identified system. A bare number or letter is ambiguous.

An inside millimeter reference

Keep the inside diameter or circumference visible so the conversion is anchored to a physical dimension rather than labels alone.

The intended maker and style

Check the target brand or jeweler's current chart and consider the intended width and inside profile before treating the result as final.

Convert one size carefully

Step 1 — Write the original label and system together
For example, keep the country or system name beside the size. Do not begin from an unlabeled number or letter.
Step 2 — Find the physical reference
Use the chart row's inside diameter or circumference in millimeters as the common reference point.
Step 3 — Read the target column from the same row
Use one chart with a named source and do not silently average or combine values from conflicting tables.
Step 4 — Check the target maker
Confirm the current chart and fit guidance for the specific maker or collection before choosing the final size.

A clear conversion record includes

Original size label and named system
Inside diameter or circumference in millimeters
Converted label and named target system
The chart source and date checked
A note that the target maker and physical fit still need confirmation

International size questions

Why do two conversion charts disagree?

They may use different increments, rounding, or manufacturer assumptions. Keep the millimeter reference visible and confirm the intended maker instead of choosing a value by guesswork.

Is the converted label exact?

No. It is a chart reference. Band width, inside profile, brand guidance, and the person's actual fit still matter.

What if I only have a number with no country or system?

Treat it as incomplete. Ask where the size came from or return to a physical diameter, circumference, or finger-gauge measurement.

Continue exploring

Follow the conversion steps
Browse rings

Related guides

Ring Size and Fit Center