You can measure your own ring size in a few ways:

Measure an existing ring
If you already have a ring that fits perfectly, measure the inside diameter in milimeters. Then compare the measurement to the ring size chart below. Make sure to measure the inside of the ring only — even a small difference can affect the size.

Use a ring sizer app or website
Use a free ring sizer app on your phone or a website. Place your ring directly on the screen and adjust the on-screen circle until it fits perfectly inside your ring. The app will show your exact size.

Measure with a string or strip
Cut a thin strip of paper, about 2mm wide or use a soft string. Wrap it gently around the base of your finger — not too tight, just snug. Mark the point where the ends meet and measure the length in millimeters, that will be your circumference. Compare your result with the ring size chart below.