What does an EU ring size actually measure?

EU ring sizes are the inner circumference of the ring in millimeters. A UK size L, for example, corresponds to roughly 52.2 mm of inner circumference, shown as EU size 52.

How do I measure my ring size at home?

Wrap a strip of paper or string around your finger, mark where it overlaps, then measure that length in millimeters with a ruler. That length is your circumference, which you can enter directly in EU to UK mode.

What if my measurement falls between two sizes on the chart?

This tool snaps to the closest listed size and shows how many millimeters off the exact match is. When in doubt between two adjacent sizes, sizing up slightly is usually more comfortable than sizing down.

Are UK and US ring sizes the same as EU sizes?

No. UK sizes use letters, US sizes use numbers on a different scale, and EU sizes use millimeters of circumference. All three describe the same physical ring, just with different scales.

Why do some charts show slightly different mm values for the same UK letter?

Ring size charts are based on standard reference tables rather than a single global law, so small rounding differences (often under half a millimeter) exist between jewelers. The values here follow the commonly used UK/EU jewelry trade chart.

UK Ring Size to EU Ring Size Converter

Name: UK Ring Size to EU Ring Size Converter
Availability: InStock
Author: Nham Vu

Pick a UK ring size letter to see its EU (mm) equivalent, or enter an EU/mm size to find the closest UK letter.

UK ring size

Full reference chart

EU size

circumference 52.2 mm · diameter 16.6 mm

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Summary

Pick a UK ring size letter to see its EU (mm) equivalent, or enter an EU/mm size to find the closest UK letter.

How it works

Choose "UK to EU" or "EU to UK" mode.
In UK to EU mode, pick your UK letter size from the dropdown.
In EU to UK mode, type the EU size or measured circumference in mm.
The matching size appears instantly, along with the ring diameter.
Scroll the reference table to see the full UK-EU chart with your row highlighted.

Use cases

Ordering a ring from a European jeweler when you only know your UK size.
Converting a partner's UK size before buying online from an EU store.
Checking a ring inherited or gifted from abroad against a local size chart.
Verifying a size printed inside a ring band against a UK sizing chart.
Comparing quotes from two jewelers that use different sizing systems.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu