How to measure my size?

METHOD 1: use soft ruler (in millimeter side)

Measure from one edge to the other across the WIDEST parts of your nails.

METHOD 2: Use paper/tape (in millimeter side)

Step 1: place paper/tape across the WIDEST parts of your nails
Step 2: use a pen to mark down the two edges
Step 3: put the paper/tape on a flat surface
Step 4: meaure the length with a ruler