Gross margin formula: find the supplier or pricing change behind the percentage
Calculate gross margin from revenue and cost of goods sold, then separate price, product mix, supplier cost, freight, discounts, waste, and inventory adjustments.
Bottom line
Gross margin is gross profit divided by net revenue. The percentage becomes useful when the business can explain the movement. A lower margin can come from discounting, product mix, supplier prices, freight, waste, or inventory adjustments, and each cause needs a different response.
Is it right for you?
- Use net revenue and COGS from the same period and scope
- Compare margin by product, customer, channel, or location where reliable
- Trace supplier price, freight, credit, and inventory changes
- Separate unit economics from changes in sales mix
Calculate the percentage without hiding the inputs
Gross profit equals net revenue minus cost of goods sold. Divide gross profit by net revenue and multiply by 100 for gross margin percentage. Keep returns, discounts, and cost classifications consistent across periods.
A margin comparison is unreliable if one month includes freight in COGS and another puts it in operating expense. Document the policy before interpreting the trend.
Use a small bridge instead of one percentage
| Illustrative item | Prior period | Current period |
|---|---|---|
| Net revenue | $400,000 | $450,000 |
| COGS | $240,000 | $292,500 |
| Gross profit | $160,000 | $157,500 |
| Gross margin | 40% | 35% |
Revenue rose in the example while gross profit fell. The next question is not whether sales grew. It is which price, mix, or cost movement consumed the additional revenue.
Give AP and operations different evidence jobs
AP can trace supplier invoices, credits, freight charges, rebates, and cutoff. Operations can explain scrap, yield, substitutions, and count adjustments. Sales can explain discounts and customer or product mix.
Reviewing those records together prevents a procurement issue from being misdiagnosed as a pricing issue, or an inventory error from being accepted as a supplier increase.
Frequently asked questions
Is gross margin the same as markup? No. Margin divides gross profit by selling revenue; markup commonly divides profit by cost.
Can revenue rise while gross margin falls? Yes. Discounts, mix, and rising direct costs can reduce the percentage and even reduce gross profit.
Why review by product? A strong category can hide a high-volume item that no longer covers its direct cost.
What AP records matter? Supplier invoices, credits, freight, rebates, purchase cutoffs, and inventory-related adjustments support the cost explanation.