Right-click on the image above and open it in a separate tab or window, then print out the image at 100%. You can cut out the ringsizer and use this to measure your finger, or wrap a strip of paper about 5mm or 1/4 inch wide snugly around your finger. Be sure to allow for the size of your knuckle that the ring will be sliding over.

Mark the point where the ends meet.

Lay the piece of paper flat and measure length either in millimeters or inches with a ruler. This is the circumference of your finger.