Product Profit Margin: How to Calculate Margin by SKU

Product profit margin shows how much of a product's selling price remains after the costs assigned to that product are deducted. For inventory decisions, the most useful starting point is usually gross margin by SKU.

Gross margin formula by SKU

Gross Margin % = (Net Sales − Cost of Goods Sold) ÷ Net Sales × 100

Example

A product sells for $40 and its unit cost is $24.

Gross profit per unit = $40 − $24 = $16

Gross margin = $16 ÷ $40 × 100 = 40%

Margin vs markup

Margin and markup are not the same.

• Margin divides profit by selling price.
• Markup divides profit by cost.

Using the same example:

Markup = $16 ÷ $24 × 100 ≈ 66.7%

Why margin by SKU matters

Revenue alone can hide weak products. A SKU may sell frequently but contribute little gross profit after product cost.

Margin by SKU helps answer:

• Which products deserve more shelf space?
• Which products are discount-sensitive?
• Which suppliers are eroding profitability?
• Which categories combine good margin with healthy turnover?

Use net sales, not sticker price

Gross margin should reflect actual net sales after discounts, refunds, and other reductions that affect realized revenue.

If a $40 product is usually discounted to $32, using the list price will overstate margin.

Use reliable product cost

The quality of margin reporting depends on cost data.

Possible product-cost inputs include:

• purchase cost
• landed cost
• freight or duties where appropriate
• costing method used by the business

Accounting treatment can vary, so finance teams should define the official cost basis used for reporting.

Gross margin vs contribution margin

Gross margin focuses on sales minus cost of goods sold. Contribution margin goes further by subtracting variable costs tied to the sale.

Contribution Margin = Net Sales − Variable Costs

Variable costs may include payment fees, marketplace fees, commissions, or shipping subsidies depending on the business.

Margin does not tell you inventory productivity

A high-margin product that barely sells can still be a poor use of inventory cash.

Pair margin with:

• inventory turnover
• sell-through rate
• GMROI
• weeks of supply

See GMROI.

Example: high margin vs high turnover

SKU A earns 55% gross margin but sells only 10 units per month. SKU B earns 35% margin but sells 100 units per month.

You should not automatically prefer SKU A. The better product depends on gross profit dollars, inventory investment, turnover, space, and strategic role.

How discounts affect margin

Discounts reduce revenue while product cost may remain unchanged.

If a $40 item with $24 cost is discounted to $30:

Gross profit = $6

Gross margin = $6 ÷ $30 = 20%

A 25% price discount cut the margin from 40% to 20%.

How returns affect product profitability

High return rates can reduce realized margin and create handling, damage, and markdown costs. Review return-heavy SKUs separately instead of relying only on original sale margin.

Margin by location

The same product can perform differently by store because of:

• different pricing
• discounting
• local demand
• waste or shrinkage
• freight or transfer cost

Multi-location operators should compare both unit margin and total gross profit by location.

Common margin mistakes

• confusing margin with markup
• using list price instead of net sales
• using stale purchase cost
• ignoring discounts and returns
• judging SKUs on percentage margin alone
• mixing accounting cost and operational estimates

How Stash helps

Stash connects product, inventory, purchasing, supplier, sales, and profitability context so physical businesses can compare product performance alongside the amount of stock invested.

Frequently asked questions

What is a good product margin?

There is no universal target. Margin expectations vary by category, business model, turnover, competitive intensity, and operating costs.

Is gross margin the same as profit margin?

Gross margin is one form of profit margin focused on net sales minus COGS. Net profit margin includes broader operating and financial expenses.

Should I discontinue a low-margin SKU?

Not automatically. Consider gross profit dollars, turnover, customer demand, cross-sell value, and strategic importance.

Next steps

Calculate margin by SKU, then compare it with inventory turnover and GMROI to see which products use inventory investment efficiently.