Worked example: a $42k/month Shopify brand
Revenue is $42,000. COGS at 32% is $13,440, fulfillment and shipping at 11% is $4,620, payment and platform fees at 6% is $2,520, and returns at 5% cost about $1,260 in unrecoverable product and shipping. Contribution margin is $20,160 — 48% of revenue. Then $7,560 of ads (18%) and $4,800 of overhead land on top, leaving $7,800 of net profit: an 18.6% net margin. Break-even revenue is roughly $16,000 a month, so the store has real headroom. Cut the ad ratio to 12% and net margin jumps past 20% — but only if revenue holds, which is the trade every DTC operator is actually making.
- • Contribution margin under 40% means ads and overhead have almost nowhere to live; fix pricing or COGS before scaling spend.
- • Returns are modeled at 60% recoverable here — you usually get the product back but lose both legs of shipping and some resale value.
- • Fixed overhead is the number founders underestimate: apps, 3PL minimums, contractors, and software creep 10–15% a year.
Gross vs contribution vs net margin
Gross margin is revenue minus COGS only — useful for comparing products, useless for judging a business. Contribution margin subtracts every variable cost of delivering the order (fulfillment, fees, returns) and tells you what each incremental sale contributes toward ads and fixed costs. Net margin subtracts those too. Investors and acquirers underwrite ecommerce on contribution margin first, because it shows whether the unit economics can ever support paid growth.
The three levers, ranked by impact
For most stores a 5% price increase adds more net profit than a 5% COGS reduction, because price flows straight to the bottom line while COGS savings are diluted by the other cost lines. The ranking is usually: (1) price and AOV, (2) ad efficiency, (3) COGS and freight. Run the target-margin input above to see the exact price lift your store needs — most operators are surprised that a 3–4% increase closes the gap.
- • AOV increases via bundles or free-shipping thresholds improve margin without touching unit prices.
- • Ad efficiency is the most volatile lever — do not build a plan that requires it to improve.
- • Renegotiate freight and 3PL rates annually; both drifted 20%+ between 2023 and 2026.
Related guides
Long-form playbooks on the same topic, written by the RevenueLab editorial team.
Shopify Conversion Rate Benchmarks 2026: What's Good for Your Vertical
Median Shopify conversion rates by vertical, the metrics that matter more than CR (AOV, repeat rate, contribution margin), and a teardown of why most stores miss their forecast.
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Read the guideFAQ
What is a good net profit margin for ecommerce?
Median DTC brands run 5–12% net. Above 15% is strong, and 20%+ usually means either high-margin products (supplements, jewelry, digital-adjacent goods) or very efficient organic acquisition. Marketplace-heavy sellers typically run lower because referral and fulfillment fees stack.
What is the difference between contribution margin and net margin?
Contribution margin subtracts only variable per-order costs — COGS, fulfillment, fees, and returns. Net margin also subtracts ad spend and fixed overhead. Contribution margin tells you whether the unit economics work; net margin tells you whether the business does.
How do I account for returns in margin math?
Model them as a percentage of revenue where you recover most of the product but lose both shipping legs, restocking labor, and some resale value — roughly 50–70% of the order value is unrecoverable. Apparel at a 20% return rate can cost 6–8 points of net margin on its own.
Why is my store profitable on paper but out of cash?
Almost always inventory timing. Net margin is an accrual figure; cash is consumed by inventory purchased months before it sells, plus payment processor holds. Track cash conversion cycle alongside net margin.
How much should ad spend be as a percentage of revenue?
Established brands typically hold 10–20% of revenue in paid media. Above 25% you are usually buying growth rather than profit, which is only rational if repeat purchase rates make first-order losses recoverable.
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