Ring Size Converter

The Global Confusion of Ring Sizing

Finding the perfect ring is romantic, but figuring out the size is often a headache. If you are shopping for jewelry on international websites (like Etsy, Amazon, or boutique European brands), you will quickly realize that sizes are not universal.

A "Size 7" in the US is roughly an "N" in the UK, a "14" in Japan, and a "54" in Europe. Our converter tool above bridges these gaps so you can buy with confidence, whether it’s for a proposal or a fashion statement.

US vs. UK vs. EU Sizing Explained

Why are there so many different systems? They developed independently based on different measurement units.

• US & Canada: Uses a numerical scale (0–16) with half and quarter sizes. It is loosely based on inches.
• UK, Australia & Ireland: Uses an alphabetical scale (A–Z). A specific letter corresponds to a specific diameter.
• Europe (ISO): The most logical system! The size is simply the circumference of the inside of the ring in millimeters. (e.g., Size 50 means 50mm circumference).

How to Measure Your Ring Size at Home

If you don't know your size, do not guess. Rings that are too tight cut off circulation, while loose rings are easily lost. Here are the two best ways to measure at home.

Method 1: The String Trick

1. Wrap a piece of string or a strip of paper around the base of your finger.
2. Mark the point where the ends meet with a pen.
3. Measure the string with a ruler in millimeters (mm).
4. This is your Circumference. Divide this number by 3.14 (Pi) to get the Diameter, then input it into our calculator above.

Method 2: Measure an Old Ring (More Accurate)

Find a ring that already fits you perfectly. Use a ruler to measure the Inside Diameter. Be very precise—even 1 millimeter makes a difference of a full size! Input this mm diameter into the "Measure Finger" tab of the calculator.

Factors That Change Your Size

Did you know your finger size changes throughout the day?

• Temperature: Cold fingers shrink; hot fingers swell. Always measure your hands when they are warm.
• Time of Day: Fingers are usually largest in the evening due to salt intake and swelling.
• Band Width: A wide band (like a thick cigar band) feels tighter than a thin wire band. If buying a wide ring, order a half size up.

International Ring Size Chart

For a quick reference, here are the most common sizes converted across major regions.