Ecommerce Contribution Margin: Formula and Example

Revenue and platform-reported return on ad spend do not tell you whether an ecommerce order created value.

What is ecommerce contribution margin?

Contribution margin is the amount left from sales after the variable costs required to generate and fulfil those sales. It contributes towards fixed overheads and profit.

A practical formula

Net sales – product cost – pick and pack – shipping subsidy – payment fees – marketplace fees – returns allowance – advertising attributable to the sale = contribution.

Contribution margin percentage = contribution ÷ net sales × 100.

Worked example

An order produces $150 in net sales. Product cost is $45, fulfilment $8, shipping subsidy $10, payment fees $4, returns allowance $6 and advertising $35.

• Net sales: $150
• Total variable costs: $108
• Contribution: $42
• Contribution margin: 28%

The $42 must still help pay wages, rent, software, professional fees and other fixed costs before the business earns profit.

Decide which costs belong in the calculation

Keep the definition consistent. Product and fulfilment costs usually belong. Whether warehouse labour, customer service or creative production is variable depends on how the business operates.

Measure by useful segments

• Product or category.
• New versus returning customer.
• Channel or campaign.
• Full price versus discount.
• Domestic versus international.
• First order versus customer lifetime.

Common mistakes

Do not use gross revenue before discounts and refunds, ignore free-shipping cost, accept ad-platform attribution as financial truth, or compare channels using different definitions.

What should you do with the number?

Use contribution margin to set allowable acquisition cost, assess discounts, prioritise products and identify where growth is consuming cash. Review it alongside cash flow and repeat purchase behaviour.

For help connecting Shopify data with commercial decisions, see Ecommerce, Shopify, SEO & AI support. Use the Monthly Pocket CEO Dashboard to incorporate the measure into a regular review.

This article provides general business information, not financial, legal, tax, employment or technology advice. Obtain advice appropriate to your circumstances.