Ecommerce Profit Margin Calculator
Build contribution margin per order from the bottom up — payment fees, fulfilment, packaging, discounts and returns — because gross margin ignores every one of them.
Ecommerce Profit Margin Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- A blended figure — per-product margins differ.
- Excludes advertising by design, since the margin sizes it.
- Measures the first order, not lifetime value.
In short: Gross margin is not what you keep. A 128.00 order at 50.12 COGS shows 60.8438% gross, but after fees, shipping, packaging, discounts and returns the contribution is 53.76 — 42.0000%, a gap of 18.8438 points.
Formula
contribution = AOV − COGS − fees − fulfilment − discounts − returns
break-even ROAS = 1 ÷ contribution margin
[('gross margin', 'COGS only — not what you keep'), ('contribution', 'after EVERY variable cost'), ('returns allowance', 'rate × (outbound + return cost)'), ('net margin', 'after fixed costs too')]
Worked Example
- Start from average order value.
- Deduct COGS, then payment fees on the full order.
- Deduct fulfilment, packaging and the discount allowance.
- Deduct a returns allowance — outbound plus return cost.
- What survives is contribution, and its reciprocal is your ROAS floor.
A 128.00 order costing 50.12 in goods shows a 60.8438% gross margin. Then reality: 4.01 payment (2.9% + 0.30), 9.60 shipping, 2.50 pick and pack, 1.20 packaging, 5.12 discount allowance and 1.69 of returns — 8% of orders costing 21.10 each in unrecovered outbound plus return handling. Variable cost totals 74.24, leaving 53.76 of contribution: exactly 42.0000%. That implies a 2.3810x break-even ROAS, not the 1.6436x gross margin suggests. At 518 orders, contribution is 27,847.68 against 18,000 fixed — 9,847.68 net, a 14.8523% net margin, and 334.82 orders just to break even.
Strengths & Limits Of This Model
Where this engine is strong
- Builds contribution bottom-up from real fulfilment costs
- Prints the gross-versus-contribution gap explicitly
- Derives the break-even ROAS and CPA the margin implies
Where it stops
- Blended across products
- First-order view
Practical Use Cases
Setting a ROAS floor
Deriving contribution margin from actual costs.
Pricing a product
Testing whether the economics survive fulfilment.
Auditing a P&L
Finding the gap between gross and contribution.
Evaluating a discount
Seeing what a promotion does to the floor.
Return policy decisions
Pricing the returns allowance explicitly.
Methodology & Editorial Standards
Contribution margin is built from the bottom up rather than assumed: cost of goods, payment processing on the full order value including its fixed component, outbound shipping, pick and pack, packaging, a discount allowance and a returns allowance. The returns line deliberately includes the outbound shipping already spent, since that money is never recovered. Gross margin is computed alongside and the gap between them is printed, because substituting gross for contribution in a break-even ROAS is the most expensive error in paid ecommerce.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Ecommerce Profit Margin Calculator — 10 Expert FAQs
10 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What is the difference between gross and contribution margin?
Gross margin deducts only cost of goods. Contribution margin deducts every variable cost of fulfilling the order — payment processing, shipping, packaging, discounts and returns. The gap is routinely fifteen to twenty points, and only contribution belongs in an advertising decision.
Why does the returns allowance include outbound shipping?
Because you paid to ship the order and never get that money back when it comes home. A return costs you the outbound shipping, the return shipping, the restocking labour, and any unit you cannot resell. Counting only the return leg understates it substantially.
Should payment fees be in contribution margin?
Absolutely. They are unavoidable, they scale with the order, and the fixed component means they hit small orders disproportionately. Leaving them out is one of the most common reasons a merchant's real margin is thinner than their spreadsheet.
What is a good ecommerce contribution margin?
It varies enormously by category, but the useful test is not a benchmark — it is whether the reciprocal produces a break-even ROAS you can actually achieve. A thirty per cent contribution margin needs a 3.33x return, which is difficult on paid social.
How do discounts affect the margin?
Directly and heavily, because a discount is a pure reduction in revenue with no offsetting cost saving. A ten per cent discount on a forty per cent contribution margin removes a quarter of your contribution, which is far more than most merchants assume.
Does contribution margin include advertising?
No, and it must not. Advertising is what you are trying to size using the margin, so including it would double-count: the reciprocal of a margin already net of media understates your break-even ROAS and produces a floor you cannot trust.
What is the difference between contribution and net margin?
Contribution covers variable costs only; net margin also absorbs fixed costs like salaries, software and rent. A healthy contribution margin with insufficient volume still produces a loss, which is why the break-even order count matters as much as the percentage.
How should I treat free shipping?
As a cost, not as an absence of revenue. If you ship free, the carrier cost still appears in your variable costs and your contribution margin falls accordingly — which is exactly why the free shipping threshold has to sit above your average order value.
Should I use blended or per-product margins?
Per-product wherever margins differ materially, because a blended figure is only valid if your sales mix matches the blend. Advertising a low-margin product against a blended-margin ROAS floor is a reliable way to lose money on your best-selling item.
What about subscription or repeat purchase?
This page measures the first order. Where customers reliably reorder, a first-order contribution below break-even can be correct strategy — but the case must rest on measured cohort behaviour, and the repeat orders carry no acquisition cost at all, which is what makes them so valuable.