Step 1: Assess whether your client could handle a .15mm lash or a .20mml lash.

Step 2: Simply change the number of lashes per fan in the first column and the calculator will tell you if that fan dimension is safe, by calculating whether it weighs more, or less, then a .15 or .20 classic lash.

NB: This formula is based off a 10mm long lash extension.