Ring Size Calculator

Convert ring inner circumference or diameter to US, UK, EU, and Japanese ring sizes with comfort fit recommendations.

Measurement Type

Measurement

Tab to move between fields

US Ring Size

UK Ring SizeUK S

EU Ring Size52.4

Japanese Size19

Comfort Fit (US)6.5

Diameter16.68 mm

Circumference52.4 mm

How to Use This Calculator

Select Measurement Type: Inner Circumference or Inner Diameter.
Measure your finger using a string or strip of paper, then enter the measurement in millimeters.
Review US Ring Size as the primary output, along with UK, EU, and Japanese sizes.
Note Comfort Fit (US) if the ring has a domed interior — comfort-fit rings size slightly larger.
Check Diameter (mm) and Circumference (mm) to confirm your measurements match the outputs before ordering.

How the result changes with Measurement

Measurement Type: Choose whether you are measuring the inside circumference or diameter of a ring.
Measurement: Enter the inner circumference or diameter of the ring in millimeters.

Identify Input Parameters
Measurement Type = 1, Measurement = 52.4 = 2 input(s) provided
Calculate US Ring Size
6 = 6
Calculate UK Ring Size
UK Ring Size = `UK ${ukSize
UK S = UK S
Calculate EU Ring Size
EU Ring Size
52.4 = 52.4

The questions that sit next to this one — chosen by subject, including calculators filed under a different category.

Convert body measurements to US, UK, and EU clothing sizes for shirts, pants, dresses, and shoes.

Convert shoe sizes between US, UK, EU, and centimeters for men, women, and kids.

Convert shoe sizes between US, UK, EU, and CM (centimeters). Includes conversions for men's, women's, and kids' shoe sizes.

Calculate how many yards of fabric you need for your sewing project based on garment type, fabric width, pattern repeat, and size.