Ring Size Converter

Convert between JP, US, EU and UK ring sizes

Find your perfect ring size for international purchases. Convert by size or find your size from ring diameter.

How to Use

Select Your Size
Choose your country and current ring size, or enter the ring diameter in mm.
View Conversions
See equivalent sizes in all major international standards.
Measure if Needed
Measure the inside diameter of an existing ring to find your size.

Ring Size Converter

Select Ring Size

Find by Diameter mm

Ring Size Chart

Diameter (mm)	Japan (JP)	US	EU	UK

Use Cases

Buying Engagement Rings Online

When purchasing engagement or wedding rings from international jewelers, use this tool to find the correct size.

Gift Shopping

Buying a ring as a surprise gift? Convert the size from your partner's existing jewelry.

Resizing Reference

Need to resize a ring purchased abroad? Use the converter to communicate the correct size.

About Ring Sizes

Ring sizing standards vary by country. Japan uses numbered sizes (1-25), US uses numbered sizes with half sizes, EU uses circumference in mm, and UK uses letters.

Measuring Your Size

The most accurate way to determine ring size is to measure the inside diameter of a ring that fits well. Use a ruler or caliper for precise measurement.

Size Variations

Ring size can vary depending on finger, weather (fingers swell in heat), and time of day. It's best to measure multiple times.

FAQ

How accurate are ring size conversions?

Conversions are approximate as different countries measure differently. For expensive purchases, we recommend professional sizing at a jeweler.

What if I'm between sizes?

If between sizes, generally size up. A slightly loose ring is more comfortable than a tight one.

Do ring sizes differ between fingers?

Yes, each finger can be a different size. The dominant hand is often slightly larger.

How do I measure ring diameter?

Place a ring that fits on a ruler and measure the inside diameter (the widest point inside the ring) in millimeters.

Are men's and women's ring sizes the same?

Yes, ring sizes are unisex. Men typically wear larger sizes (JP 16-23) while women typically wear smaller sizes (JP 8-15).

Can ring size change over time?

Yes, ring size can change due to weight fluctuations, aging, pregnancy, and other factors. It's good to remeasure periodically.