How discounts affect ecommerce profit margin

Discounts change the revenue base for margin math. They reduce net revenue before COGS is subtracted — they are not a separate expense line in gross margin. Mis-handling them is a common way to overstate margin.

The calculation order

Net revenue = gross sales − discounts
Gross profit = net revenue − COGS
Gross margin = gross profit ÷ net revenue

COGS does not change because you ran a sale. What changes is net revenue and the dollars left after product cost.

Single-order example

Using $100 as revenue would incorrectly show 60% margin ($60 ÷ $100). The correct base is $80 net revenue. A promotion that doubles units but cuts net revenue per unit can still reduce total gross profit — compare gross profit dollars with and without the campaign.

Discount types to track

• Cart-wide percentage or fixed amount codes
• Automatic collection or tag discounts
• Bundled set pricing below component sum
• Marketplace subsidies recorded as discounts in exports

Analyze by product

Store-level discount rate hides SKUs that are always on sale. Line-level exports show which products absorb the most discount dollars relative to gross sales.

Contribution margin angle

Contribution = gross profit − optional variable costs

Deep discounts plus free shipping plus paid acquisition can compress contribution even when gross margin looks acceptable. Review both when evaluating promotions.

Review checklist

• List top SKUs by discount dollars in the period
• Compare their gross margin to store average
• Protect price on SKUs that sell steadily with little discount
• Retire always-on promotions that no longer need to run

Exports and next steps

Use order exports that separate gross sales and discount amounts per line. Then model the period in the calculator and upload product data to see which discounts correlate with weak SKU margin.