What is math equation to formulate hair color?

Answer 1

Example using a level 8 blonde. Obviously, substitute your hair color level and desired shade.

Desired color-Warm Blonde Level = Level 8

Target color level X 2 = 16

Natural color-Light Ash Brown = Level 6

subtract this from target color level of 16 16-6=10

This gives you the number of levels to lift (= 2) and the level of color to use (=10).

Note: If the total number for the level of color is 13 or larger, pre-lightening is required to achieve the desired color. You need to go off to a professional for double process coloring.