To find the right size, you will need to take measurements of each of your nails. You can do this with a soft measuring tape or with tape and a ruler.
To measure with tape:
Step 1: apply a strip of tape over your nail and press down on the sides of the crease
Step 2: use a pen to mark each side of the nail in between the creases
Step 3: remove the tape and place on a flat surface and measure in millimetres
