How to Calculate Profit Margin — Formula, Examples, and Common Mistakes

If you’ve ever stared at a sale, watched the platform deduct a fee, paid for the ad that brought the buyer, paid the supplier, and ended up wondering where your profit went — this guide is the math you needed. Profit margin is not one number. It’s a chain of three numbers, and most ecommerce sellers confuse them.

The three margins (in order of strictness)

1. Gross margin — Revenue minus the direct cost of the product. Doesn’t include any platform fees, ads, or overhead. Useful for: deciding which SKUs are even worth listing.

Gross margin = (Revenue − COGS) ÷ Revenue

2. Contribution margin — Gross margin minus the variable costs attached to making each sale happen (platform fees, payment processing, fulfillment, advertising). Useful for: deciding whether a price point is viable on a specific channel.

Contribution margin = (Revenue − COGS − variable selling costs) ÷ Revenue

3. Net margin — Contribution margin minus your fixed costs (subscriptions, app costs, salary, rent, software). This is what actually lands in your bank account. Useful for: deciding whether the business itself is profitable.

Net margin = (Revenue − all costs) ÷ Revenue

Most ecommerce founders quote gross margin when bragging and net margin when explaining why they can’t pay themselves. Both are accurate; they’re just measuring different things.

A worked example: $30 Etsy product

Let’s walk through all three on the same sale. You sell a handmade ceramic mug for $30 (shipping included) on Etsy.

Costs:

• Materials (clay, glaze, electricity): $4
• Your labor at $15/hour, 20 minutes: $5
• Etsy listing fee (allocated): $0.20
• Etsy transaction fee: 6.5% of $30 = $1.95
• Etsy payment processing: 3% + $0.25 on $30 = $1.15
• Shipping (paid by you, included in price): $4.50
• Cost of materials packaging: $0.50

Gross margin = ($30 − $4 − $5 − $4.50 − $0.50) ÷ $30 = $16 ÷ $30 = 53.3%

That’s a healthy gross — handmade should be high-gross by nature, because the labor is the value.

Contribution margin = $16 − $0.20 − $1.95 − $1.15 = $12.70 ÷ $30 = 42.3%

After Etsy takes its cut, you’re still in good shape. If you ran an Offsite Ad and Etsy took another 15% ($4.50), contribution margin drops to 27.3%.

Net margin = subtract your fixed monthly costs (Etsy Plus $10/mo if you use it, accounting software $30/mo, Canva $13/mo, etc.). Divide those across your monthly sales count. For a 50-mug/month seller, fixed costs of $53 ÷ 50 = $1.06/unit, leaving 38.8% net margin (before Offsite Ads) or 23.8% (with them).

Plug the same numbers into the Etsy Fee Calculator and you’ll see this breakdown live with every fee linked to its Etsy source page.

Markup vs. margin — the eternal confusion

This is the single biggest math mistake in ecommerce. Markup and margin measure the same dollar amount of profit, just relative to different bases:

Notice that markup can exceed 100% (you can mark something up infinitely), but margin caps at 100% (you can’t keep more than the entire sale price).

Formulas:

Markup = (Sell price − Cost) ÷ Cost
Margin = (Sell price − Cost) ÷ Sell price

Converting between them:

Margin = Markup ÷ (1 + Markup)
Markup = Margin ÷ (1 − Margin)

Why this matters: suppliers and wholesalers typically quote in markup (“a 100% markup on cost”), while finance teams and analysts quote in margin (“we need a 50% gross margin”). When somebody says “we run at 40%”, always confirm which side of the equation they mean. A “40% markup” on a $10 cost is a $14 price with $4 profit, only a 28.6% margin — way below most ecommerce profitability benchmarks.

The three pricing approaches

Once you’ve fixed the markup/margin confusion, you can price three ways:

1. Cost-plus pricing — Take cost, apply markup. Common in wholesale and traditional retail; rare in ecommerce because it ignores what the market will pay.

2. Target-margin pricing — Decide your required net margin first, then back-solve the price. This is what we recommend. Example: you need 25% net margin on Amazon FBA, you know the all-in fee load is ~32% of revenue, COGS is $8. Solve:

Price × (1 − 0.32 − net_margin) = COGS
Price × (1 − 0.32 − 0.25) = $8
Price × 0.43 = $8
Price = $18.60

So you need to sell at $18.60 minimum. Compare against market comparables; if the market is at $14, this product can’t profitably exist on Amazon FBA for you.

3. Market-anchored pricing — Survey competitors, price within the band, then squeeze your costs to hit margin targets. Most successful established ecommerce sellers do this; it requires already having efficient supply chains.

What healthy margins look like in 2026

These are net margin benchmarks from public DTC brand financials and seller surveys:

“Survival floor” is the level below which one bad month (return spike, ad cost increase, seasonal storage surcharge) takes you negative.

Common mistakes to avoid

1. Quoting gross margin when you mean net. Investors and acquirers will spot this immediately; founders sometimes do it innocently. Always specify.
2. Forgetting to allocate fixed costs. If you have $500/month in Shopify apps, that’s $5 per unit at 100 units/month. It comes out of margin.
3. Ignoring refund/return rates. A 20% return rate on apparel doesn’t just lose you 20% of revenue — it costs you the FBA return processing fee, restocking labor, and write-off of damaged units. Build returns into your COGS line.
4. Not separating advertising for new customers vs existing. Acquisition ad spend should be allocated against new-customer LTV, not first-order margin. If you’re scaling, “losing money on first order” is sometimes correct strategy.
5. Assuming margin scales linearly with price. Doubling the price doesn’t double the margin — fixed costs get spread thinner, but variable costs (payment processing % component) scale with price too.

Related reading

• Amazon FBA Fees Breakdown 2026
• Shopify Plans 2026: Basic vs Shopify vs Advanced
• Glossary: gross profit, net profit, markup vs margin, ACoS, ROAS