Ecommerce Unit Economics: A Sydney Virtual CFO Guide (2026)
A virtual CFO guide to ecommerce unit economics for Sydney founders. From blended gross margin to real contribution per order, with a worked ladder.
An ecommerce business can post a healthy gross margin and still lose money on every second order. The reason is that gross margin sits near the top of the P&L, and most of the cost that decides whether a sale is profitable sits below it. This is a virtual CFO's walk through ecommerce unit economics: from the blended margin that flatters the business to the contribution per order that actually runs it.
Published: July 2026
Gross margin is the first number a founder learns and the last one they should trust on its own. It is revenue minus the cost of goods sold, and on the dashboard it usually looks reassuring. The problem is what it leaves out. Once you fold in the full landed cost of goods, freight-in and duties included, most Australian mid-market brands land materially lower than the headline. And once you go past gross margin into the variable cost of fulfilling and acquiring each order, the picture changes again.
The number that decides whether the business works is not gross margin. It is contribution margin per order, and it lives several lines further down. If you want that model built across the whole business rather than one order, it is one of the four deliverables in the 90-Day Number. This article is the logic underneath it.
For calibration: reported DTC gross margins commonly span 40 to 70 per cent depending on category, with beauty near the top and food and beverage near the bottom. A range that wide is nearly useless on its own, which is rather the point. Where your brand sits inside it matters less than what happens below the line, and if the comparison itself is your question, we keep a separate page on ecommerce gross margin benchmarks.
Contribution margin is what one order contributes after every cost that varies with the order itself. Fixed costs, rent, salaries, software, sit below it and are covered out of aggregate contribution, not per sale.
Start with average order value (AOV), the actual revenue per order after discounts and excluding GST. Then subtract, in order:
What remains is contribution per order. Everything above it is variable and belongs in the calculation. Everything below it is fixed and does not.
Take a Sydney DTC brand with an AOV of $120 and a reported gross margin that looks strong on the dashboard. Assumptions, so you can check the arithmetic: landed COGS at 35 per cent of AOV, a blended processing rate of 3 per cent, an 8 per cent return rate at roughly $60 all-in per return event (return freight, handling, and margin lost on units that cannot be resold at full price), and advertising averaged across new and repeat orders. Walk the order down the ladder:
Contribution per order is $27.60, or about 23 per cent of AOV. That is a viable business. But notice how far it travelled from the 65 per cent gross margin the founder started with. Forty-two points of margin disappeared into costs that never touch the gross margin line.
Now run the same brand's free-shipping tier. Suppose orders under $80 still ship free, and a promotion pulls the AOV on that cohort down to $60. The cost stack does not shrink proportionally. Landed COGS falls with the smaller basket, but fulfilment, the returns provision, and the ad spend to win the customer barely move.
That order loses $9.60. Every new customer acquired at the $60 basket costs the brand $9.60 for the privilege. Blended across all orders, the profitable $120 orders subsidise the loss-making $60 ones, and the P&L shows a modest profit that hides a whole tier of the business sitting underwater. This is the single most common finding in an ecommerce unit economics build, and it is invisible until you go per order. A per-order model surfaces it immediately; a 13-week cashflow forecast shows what it is doing to cash while the P&L stays polite.
Analysts talk about contribution margin in levels, and the distinction matters when you decide which lever to pull.
Contribution margin 1 is revenue less landed COGS: gross margin, essentially. Contribution margin 2 subtracts fulfilment and payment processing, the cost of getting the product to the customer and taking their money. Contribution margin 3 subtracts variable marketing, the cost of winning the order. CM3 is the number that tells you whether growth is profitable, because it is the last line before fixed costs.
A brand can have a strong CM1 and a negative CM3 if acquisition is too expensive. That is a marketing problem, not a product problem, and the fix is different. Knowing which level breaks is the difference between cutting ad spend and renegotiating your freight contract, and in a virtual CFO engagement for an ecommerce brand, the level that breaks is what sets the work plan.
One more trap worth naming. Founders often measure customer acquisition cost blended across all orders, which mixes cheap repeat purchases with expensive first purchases and makes acquisition look more efficient than it is. The honest cut is first-order CAC: what it costs to win a first-time customer.
The direction of travel makes this worse, not better. SimplicityDX's analysis of the customer acquisition crisis has average ecommerce acquisition costs up roughly 60 per cent over five years, with Apple's 2021 privacy changes and the loss of precise ad targeting doing much of the damage. A brand still working from its 2021 acquisition maths is almost certainly underestimating what growth now costs.
If first-order contribution is negative, the business is betting on the second order to recover the loss. That bet is only as good as the repeat rate, and the repeat rate is a number you measure with cohort analysis rather than assume.
If the unit economics come back negative at the contribution line, there are only a few real levers, and adjectives are not among them.
Raise AOV so the flat per-order costs (fulfilment, the fixed part of processing, the returns provision) spread across more revenue. Lift the repeat rate so blended CAC falls. Cut the return rate with better sizing, fit guides, and product information. Renegotiate freight and processing at scale. Or reprice, if the market allows it. Everything else is a temporary patch. The order either contributes or it does not, and the fix has to change one of the lines in the ladder above. Before committing to any of them, pressure-test the move: that is scenario modelling work, and it is cheaper than finding out in market.
This is founder-side work you can run yourself with the framework above. Where a virtual CFO earns the fee is building it once, properly, across every SKU and channel, so the answer is defensible rather than approximate. Most Australian virtual CFO engagements are monthly retainers; ours is a project. The unit economics build is one of the four named deliverables in the 90-Day Number, fixed at $17,850 plus GST, and on day 90 the model is yours to run.
What is the difference between gross margin and contribution margin?
Gross margin is revenue less the cost of goods sold. Contribution margin goes further and subtracts every other cost that varies with the order: fulfilment, payment processing, returns, and variable acquisition spend. Gross margin tells you whether the product is priced above its cost. Contribution margin tells you whether selling one more unit makes money.
What is a good contribution margin for a DTC brand?
As a working range, a DTC brand carrying paid acquisition usually needs contribution somewhere around 15 to 25 per cent of AOV at the CM3 level for the fixed cost base to fit underneath it, though the spread by category and channel is wide. The more useful question is not whether you hit a range but whether your aggregate contribution covers your fixed costs at your current volume.
What payment processing rate should I use in my model?
For an Australian brand, a domestic card on Stripe is 1.7 per cent plus 30 cents, and Square's online rate is 2.2 per cent flat. Model your blended effective rate, not the headline, because buy-now-pay-later and international cards push the real number to 3 to 5 per cent of revenue for many brands. Pull twelve months of processor fees, divide by net revenue, and use that.
How do returns fit into unit economics?
Returns are a variable cost and belong in the contribution build. Provision for them across all orders based on your actual return rate, and include return freight, handling, and the margin lost on units you cannot resell at full price. On $10M of gross sales, cutting the return rate by 5 percentage points retains roughly $500,000 of revenue that would otherwise be refunded, before counting the freight and handling saved, which is why tracking returns by SKU rather than in aggregate pays off.
Should I use first-order or blended CAC?
Both, for different purposes. First-order CAC tells you whether acquiring a new customer is profitable on the first order. Blended CAC flatters the number by mixing in cheap repeat purchases. If you only track one, track first-order, because that is the one that exposes whether growth is funded by profit or by hope.
Why does my accountant's P&L not show contribution margin?
Because a statutory P&L groups costs by type, not by order. Ad spend sits in operating expenses, freight gets split across lines, and returns net quietly out of revenue. Nothing is wrong with the accounts; they are answering a compliance question. Contribution margin is a management build, assembled from the order data, and someone has to construct it deliberately.
Can a virtual CFO build this for my business?
Yes. A unit economics build is one of the four named deliverables in the 90-Day Number. It produces a per-order and per-SKU contribution model you can run yourself, which is the point: the deliverable is yours after day 90, not a report you have to keep paying to read.
My gross margin is 60 per cent but my bank balance is falling. Why?
Almost always because contribution margin is far below gross margin, and fixed costs plus growth investment are consuming what little contribution remains. Gross margin at 60 per cent can coexist with contribution at 20 per cent and a business that burns cash to grow. The gross margin line is not lying; it is just answering a different question from the one your bank balance is asking.
Sydney Virtual CFO is a Sydney-based virtual CFO service for founders running $2M to $15M businesses across SaaS, ecommerce, professional services, construction, and other low-volume, high-value industries. We deliver fixed-scope CFO engagements with a named deliverable on day 90: a 13-week cashflow forecast, a fundraise-ready financial model, a unit economics build, or a board reporting pack you can run on your own.
Our front-door product, the 90-Day Number, is fixed scope at $17,850 plus GST. We are one of the few project-based virtual CFOs in Australia, in a market built almost entirely on monthly retainers. No retainers without a deliverable. No 80-page reports. No theatre.
This content is general information only, written for Australian founders running businesses in the $2M to $15M revenue range. It does not constitute tax, financial product, investment, or legal advice and should not be relied on as such. The work referenced is led by a Chartered Accountant (CA ANZ), but Sydney Virtual CFO is not a licensed tax agent, not a licensed financial adviser, and not authorised to provide personal financial advice. Tax obligations, accounting treatments, fundraise terms, and statutory requirements depend on your individual circumstances. For advice specific to your business, contact the team directly or consult a registered tax agent, licensed financial adviser, or qualified lawyer. Information was current at the time of publication and may change without notice. We review and update guides periodically.
