Ring Size Calculator

Calculate by Ring Diameter

Measure the diameter of a ring that fits you well, then input the measurement below.

Your Ring Size Results

US Size

UK Size

EU Size

Japan Size

Measurement Details

Diameter:

Circumference:

International Ring Size Comparison

US Size	UK Size	EU Size	Japan Size	Diameter (mm)	Circumference (mm)

Sizing Recommendations

Measure your finger at the end of the day when it's warmest, as fingers can shrink in cold weather.
If your knuckle is larger than the base of your finger, measure both and choose a size that fits comfortably over the knuckle.
For wide band rings (wider than 6mm), consider sizing up by half a size.

How to Use the Ring Size Calculator

Choose a Measurement Method

Select from one of the four measurement methods: by diameter, by circumference, string method, or using an existing ring that fits well.

Take Your Measurement

Follow the instructions for your chosen method to take an accurate measurement of your finger or existing ring.

Input Your Measurement

Enter your measurement into the calculator, making sure to select the correct unit of measurement (millimeters, centimeters, or inches).

Get Your Results

Click the calculate button to get your ring size in multiple international sizing systems, along with additional sizing recommendations.

Frequently Asked Questions

What is the most accurate way to measure ring size? +

Do fingers change size throughout the day? +

Should I size up for wide band rings? +

How do I convert between different ring size systems? +

What if my knuckle is larger than my finger? +

Free Calculator