Should I measure before using the converter?

Yes. Measure at home with string, tape, an existing ring, or our printable sizer, note millimeters (or centimeters), then use By Measurement—or convert a known US, UK, or EU label.

Is this a ring size calculator?

Yes. Size Conversion converts a known label. By Measurement is the calculator: enter circumference or diameter and get the closest US, UK, and EU size.

What is 6 cm in ring size?

Treat 6 cm as circumference, not diameter: 6 cm = 60 mm around the finger, which lands near US 9¼ (UK S, EU ~60) on our chart. Use Circumference (cm) in By Measurement. Do not read 6 cm as inside diameter.

What measurements do I need?

Circumference or inside diameter. Rulers often show cm—choose Circumference (cm), or multiply by 10 for mm. Jewelers list sizes in mm. You can also measure an existing ring’s inner diameter.

How do I convert my ring size between different countries?

Select your current region and size, pick the target region, and convert. Or skip labels and enter a measurement instead.

Turn Finger Measurements into a Ring Size

Use By Measurement to enter circumference in mm or cm (6 cm = 60 mm), or convert a known US, UK, or EU label. Not measured yet? Measure ring size at home first.

Ring Size Converter

From region

Size

To region

Please check your input

No US ring size “7” in our chart. Double-check the number or letter, or pick a nearby size from the table. Try 7, 6, 8.

Converter data sources

Rows map inside diameter and circumference in mm to US numbers, UK letters, and EU circumference labels. Jewelers can still round differently—confirm with a physical sizer.

ISO 8653 jewellery — ring-sizes
Standard / specification · Last checked: 2026-10-05
https://www.iso.org/standard/44534.html
SizeFit how to measure ring size
Secondary source · Last checked: 2026-10-05
https://sizefit.org/guides/how-to-measure-ring-size

Full method: How we source size data

Turn Finger Measurements into a Ring Size

Related Tools & Guides

Measure at home

Printable ring sizer

Ring size chart (mm)

Men's ring size chart

Women's ring size chart