Wrap the paper snugly around the base of the finger you want the ring for. Make sure it's tight enough not to slip off, but loose enough to be comfortable.

Mark the point where the paper overlaps.

Unwrap the strip and use a ruler to measure the length in millimeters (mm) from the end to the mark. This is the circumference of your finger.

Use the ring size chart to convert the circumference in mm to your corresponding US ring size.