From Wikipedia, the free encyclopedia. Phototoxicity, also called photoirritation, is a chemically induced skin irritation, requiring light, that does not involve the immune system. It is a type of photosensitivity. The skin response resembles an exaggerated sunburn.
Contribution margin ratio measures the percentage of sales that would increase net income. To calculate it, divide contribution margin by sales, either in total or per unit: Suppose a gadget selling for $100 per unit brings in $40 per unit of contribution margin.
Formula or equation of CM ratio is as follows: [ CM Ratio = Contribution Margin / Sales ]. (Above can be modified as contribution margin percentage formula ,incremental contribution margin formula, average CPR formula, cvp formula, unit or segment break even point.This ratio is extensively used in cost volume profit calculations.he contribution margin as a percentage of total sales is referred to as contribution margin ratio (CM Ratio).