Contribution margin, or dollar contribution per unit, is the selling price per unit minus the variable cost per unit. `Contribution” represents the portion of sales revenue that is not consumed by variable costs and so contributes to the coverage of fixed costs. This concept is one of the key building blocks of break-even analysis. In cost-vol.....
A per unit measure of profit margin: contribution ÷unit price, or total contribution ÷revenue....more on Contribution margin
The difference between variable revenue and variable cost. 
Contribution margin:
The difference between variable revenue and variable cost.The total amount paid to the business for its common and preferred stock.
The difference between revenue per unit and variable cost per unit, in the framework of break-even analysis.
Contribution margin is the amount of sales revenue that exceeds variable costs. In other words, this is the amount of revenue that can be used to pay for?fixed costs?after all of the?variable costs?have been paid.