Revenue growth can mask a broken business model for a surprisingly long time. A business can be generating millions of dollars in revenue, growing at 40% per year, attracting investor interest — and still be fundamentally unviable if the economics at the unit level do not work.
Unit economics is the discipline of examining the financial performance of your business at the most granular level — the individual customer, the individual transaction, or the individual unit of product sold. When the unit economics are strong, you can be confident that growth will produce more profit. When they are weak, growth simply amplifies the loss.
What Are "Units"?
The definition of a "unit" depends on your business model:
- For a subscription business: a single customer (their recurring revenue vs the cost to acquire and serve them)
- For an eCommerce business: a single order (revenue minus all variable costs to fulfil it)
- For a project-based services firm: a single project (revenue minus direct delivery cost)
- For a product manufacturer: a single unit sold (selling price minus cost of goods)
- For a hospitality business: a single cover (average spend per head minus food and direct labour cost)
The concept is the same across all models: strip away the overhead and look at the contribution that a single unit of activity makes.
The Core Unit Economics Metrics
Contribution Margin Per Unit
This is the most fundamental unit economics measure. It is the revenue per unit minus all variable costs directly attributable to producing or delivering that unit.
Contribution margin = Revenue per unit − Variable cost per unit
A positive contribution margin means each unit sold is contributing something toward overhead and profit. A negative contribution margin means you are losing money on every unit you sell — and no amount of growth will fix that; it will only make it worse.
Customer Acquisition Cost (CAC)
For businesses where the unit is a customer, CAC is a critical metric:
CAC = Total sales and marketing spend ÷ Number of new customers acquired
CAC should include all costs associated with acquiring customers: advertising, sales team salaries and commissions, marketing agency fees, trade show costs, referral fees. A common error is to include only direct advertising spend and ignore the human cost of the sales process.
Customer Lifetime Value (LTV)
LTV is the total profit a customer generates over their entire relationship with your business.
LTV = (Average revenue per customer per period × Gross margin %) × Average customer lifespan
Or, for a subscription business:
LTV = (Monthly recurring revenue per customer × Gross margin %) ÷ Monthly churn rate
The LTV:CAC Ratio
The relationship between LTV and CAC is the defining unit economics indicator for customer-based businesses.
- 3:1 or above: Generally considered healthy and scalable
- 1:1 to 3:1: Marginal — growing this business will be expensive and risk-laden
- Below 1:1: Every customer you acquire destroys value — stop scaling until this is fixed
Payback Period
The payback period tells you how long it takes to recover your customer acquisition investment:
Payback period = CAC ÷ Monthly contribution margin per customer
Short payback periods (under 12 months) indicate a self-funding growth model. Long payback periods mean you need significant working capital to fund growth.
Why Unit Economics Often Look Worse Than Expected
Many businesses calculate their unit economics and are surprised — and not pleasantly — by the result. There are several common reasons the numbers look worse than expected:
Underestimating variable costs. It is easy to miss secondary variable costs: credit card processing fees, packaging materials, returns and credits, customer success staff time on a per-customer basis. Every variable cost that flows from an additional unit of activity needs to be in the calculation.
Including fixed cost savings that are not yet real. At low volumes, many costs are effectively fixed. At higher volumes, some may genuinely become variable. Be honest about which costs actually scale with volume and which do not.
Not accounting for churn. For subscription or repeat-purchase businesses, the LTV calculation is highly sensitive to churn rate. A small increase in churn significantly reduces LTV. Many businesses are optimistic about retention in their LTV models.
Not separating new customer CAC from blended CAC. Blended CAC (total marketing spend divided by total customers acquired, including repeat customers) is almost always lower than new customer CAC. For unit economics purposes, new customer CAC is the relevant number.
Fixing Weak Unit Economics
If your unit economics are not working, there are a limited number of levers:
Increase Revenue Per Unit
- Raise prices (if the market allows)
- Increase average order value through upselling or bundling
- Improve retention to extend customer lifespan (increases LTV without changing CAC)
Reduce Variable Cost Per Unit
- Renegotiate supplier costs
- Improve operational efficiency in delivery
- Reduce returns and rework
- Optimise fulfilment and logistics
Reduce Customer Acquisition Cost
- Improve conversion rates (the same ad spend acquires more customers)
- Shift toward lower-cost channels (organic, referral, content)
- Improve targeting to reduce wasted spend
Accept the Reality of the Business Model
Sometimes the honest conclusion is that the business model does not work at its current price point, cost structure, or market position. That is an important insight — painful, but valuable. It is far better to identify a broken unit economics model when the business is small than to scale it into a much larger problem.
Unit Economics in the Australian Context
For Australian businesses, unit economics calculations need to account for specific cost structures:
- Superannuation is a genuine variable labour cost — 11.5% of base wages as of 2024–25 — and should be included in any labour cost used in unit economics calculations
- GST is a pass-through tax, not revenue — always work from ex-GST revenue in unit economics
- PayG withholding and payroll tax thresholds (which vary by state) affect the true cost of labour
If your unit economics are positive and strong, you have a business worth scaling. If they are not, you have the most important work in the business to do before anything else.
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