Contribution Margin

Contribution margin is the revenue an e-commerce brand keeps from an order after deducting that order's variable costs: cost of goods sold, shipping, payment processing fees, and pick-pack-fulfilment. It can be expressed per order in currency (contribution margin per order) or as a percentage of revenue (contribution margin %). Because it isolates the costs that scale with each sale, it is the figure operators use to judge whether an additional order actually adds money rather than just adding GMV.

For an affiliate operator, contribution margin is the ceiling on the commission rate the program can afford. If a typical order has a 35% contribution margin before commission, paying a 40% commission on revenue would turn that order into a loss. Many DTC brands therefore set affiliate commission as a share of contribution margin instead of a flat share of revenue, so payouts flex with product mix, discounting, and shipping cost rather than rewarding low-margin or heavily couponed orders at the same rate.

Contribution margin interacts directly with average order value and customer acquisition cost. A higher average order value usually lifts contribution margin per order because fixed per-order costs like payment fees are spread over more revenue, while acquisition cost (including affiliate commission) is the spend that contribution margin must repay. A program is sustainable when the contribution margin earned across a referred customer's orders exceeds the cost of acquiring them.

Operators running an ecommerce affiliate program increasingly model commission against contribution margin per SKU rather than a single blended rate, paying more on high-margin lines and less on thin-margin ones. This keeps the channel profitable even when affiliates push promotional or clearance inventory.