We use Standard US size for all of our rings (8, 9, 10, etc)
Wrap a piece of paper (no wider than 3/4″) or string around the base of the appropriate finger tightly like a ring, but comfortably, with enough room to slide over the knuckle.
Mark and measure the length of the paper or string used to wrap around your finger, in millimeters, and check it against our size chart.
You are using the paper or string to create a ring that you can measure.
If your ring size falls between 2 sizes we recommend you choose the size up.