How do I measure my ring size at home?

Wrap a strip of paper or thin string around the base of your finger, mark where it overlaps, then measure the length in millimeters. That is your finger circumference. Use this tool to map it to any standard.

What is the difference between EU and US sizing?

EU sizes are based on the inner circumference of the ring in millimeters (ISO 8653). US sizes use an arbitrary numerical scale where each full size step equals roughly 0.832 mm in inner circumference. An EU 53 is approximately a US 6 (inner circumference ≈ 52.5 mm).

Are UK and Australian ring sizes the same?

Yes. The UK, Australia, Ireland, and South Africa all use the same letter-based system running A through Z+6. A UK size L is exactly the same as an Australian size L.

How accurate is this converter?

The table uses standard published mappings. Ring sizing can vary slightly between jewelers due to measuring technique and band width. For important purchases, always have your finger measured by a professional jeweler.

What is a Swiss ring size?

Swiss sizes are a numerical scale starting at 1. Swiss size 6 corresponds roughly to EU 46, and Swiss size 27 to EU 67. The scale is popular in Switzerland and parts of continental Europe.

Why does band width affect fit?

A wider band sits higher on the finger and feels tighter than a narrow band of the same inner diameter. For bands over 6 mm wide, many jewelers recommend going half a US size up.

Ring Size Converter

Convert ring sizes between US, UK, EU (ISO), Japanese, and Swiss standards using finger circumference in mm as the anchor measurement.

Convert Ring Size

Input standard

Size value

Full Size Chart

Circ. (mm)	EU / ISO	US	UK	JP	Swiss

Summary

This converter maps ring sizes across five major international standards: US/Canada, UK/Australia/South Africa, EU/ISO (inner circumference in mm), Japanese/Chinese, and Swiss. Enter a size in any standard or type a finger circumference in millimeters and the tool shows exact or nearest equivalents for every standard. All data uses published ISO 8653 and trade-standard tables; no rounding beyond half-size steps.

How it works

Select an input standard from the dropdown (US, UK, EU, Japanese, Swiss, or mm circumference).
Enter your ring size value in the input field.
The tool looks up the matching row in the size table and displays all equivalent sizes.
If your value falls between two rows, the nearest match is highlighted.
Use the full reference table at the bottom to compare all standards side by side.

Use cases

Convert a US ring size to EU before ordering from a European jeweler.
Find the Japanese equivalent of a UK size when shopping on Japanese marketplaces.
Measure finger circumference and map it to any regional standard.
Compare Swiss and EU sizes when resizing a watch ring or ring guard.
Verify a ring size before purchasing an engraved or non-returnable piece.
Help a friend abroad buy a ring as a gift without the recipient knowing their size.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu