Contribution Margin

Contribution Margin is defined as Sales less Variable Costs. Variable Costs are the expenses that are tied to the sale of each unit. They are recognized when a unit is sold. Because the number of units you sell varies with demand, they are called Variable Costs. In the example above you sold 1 million units. If you had sold 2 million, your Variable Costs would have been $38 million, but if you sold 500 thousand, they would be only $9.5 million.

In short, you do not know your Variable Costs until the sales numbers arrive.

Period Costs, on the other hand, are not tied to sales. In the example above, you spent $5.2 million on Period Costs whether you sold anything or not. While you could not say what your Variable Costs were until December 31st, the Period Costs were known on January 1st.

Net Margin is defined as Contribution Margin less Period Costs. Put simply, it is what the product contributes towards profits.

From the combined Net Margin (normally across all products) you pay the expenses that cannot be allocated to a product. First comes "Other" (expenses like brokerage fees), then Interest, Taxes, and Profit Sharing until you are left with a Net Profit.