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.
The contribution margin ratio is the difference between a company's sales and variable expenses, expressed as a percentage. The total margin generated by an entity represents the total earnings available to pay for fixed expenses and generate a profit.
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).