Ring Size Converter
Convert US ring sizes to approximate UK letters, EU circumference and inside diameter.
How to Use the Ring Size Converter
Enter a known ring size or finger measurement and convert between common US, UK and EU sizing systems. Use an accurate diameter or circumference when available.
Practical Example
A ring with an inside diameter near 17.3 mm is approximately a US size 7. Equivalent sizes can vary slightly by chart.
Factors That Affect Ring Fit
Finger temperature, time of day, ring width, knuckle size and manufacturer tolerances can affect fit. Measure more than once before ordering jewelry.
Frequently Asked Questions
Should I measure diameter or circumference?
Either works if measured accurately, but circumference is often easier with a flexible strip.
Do ring sizes match perfectly between countries?
No. International charts use different increments, so converted sizes may be approximate.
Does a wide band fit differently?
Yes. Wider rings often feel tighter and may require a slightly larger size.
Understanding Ring Size Conversions
Ring size systems use different labels in the US, UK, Europe and other regions, while inner diameter or circumference provides a more direct physical measurement. Conversion charts are therefore approximate when manufacturers use slightly different tolerances.
Measure an existing well-fitting ring or finger circumference at normal temperature, and consider knuckle size and band width. For expensive or permanent purchases, confirm the converted result against the seller’s own sizing chart.
Conversion Details and Practical Limits
Mass conversion changes units without accounting for local gravitational force because kilograms, pounds-mass and similar units describe mass. Do not confuse mass with force units such as newtons or pounds-force in engineering calculations.