Unit Economics: Formula, LTV/CAC & Benchmarks

What Is Unit Economics?

Unit economics refers to the revenue and costs associated with a single unit of a business, usually one customer. It isolates whether that unit is profitable on its own, using contribution margin, customer acquisition cost, lifetime value, and payback period rather than company level totals.

How Unit Economics Works

Unit economics starts by choosing the unit. For subscription software it is one customer or one account. For a marketplace it is one transaction. The choice matters because every downstream number is defined against it, and comparing two companies that picked different units produces nonsense.

Once the unit is fixed, revenue and cost are separated into variable and fixed. Variable costs scale with the unit: hosting, payment processing, third party data, and the support hours that customer consumes. Fixed costs, such as the engineering team and the office, stay out, because they do not move when one more customer signs. What remains after variable costs is contribution margin, the money each customer contributes toward covering fixed costs and eventually profit.

Aggregate metrics hide the answer. A company can grow revenue 80 percent a year while losing money on every customer it adds, and the income statement will not say so until growth slows. Unit economics is the check that catches it early.

How to Calculate Unit Economics

Formula: Contribution Margin per Customer = Revenue per Customer - Variable Cost per Customer

Take a B2B software company with an average contract value of $12,000 a year. Variable costs per customer are $900 of hosting, $300 of payment processing, $1,200 of customer support, and $600 of third party data, or $3,000 total. Contribution margin is $12,000 minus $3,000, or $9,000 a year, a 75 percent gross margin.

Now bring in acquisition cost. The company spent $900,000 on sales and marketing last quarter and added 50 customers, so CAC is $18,000.

Formula: LTV to CAC Ratio = Lifetime Value / Customer Acquisition Cost

At 20 percent annual churn the average customer stays five years, so lifetime value is $9,000 times 5, or $45,000. Divide by an $18,000 CAC and the LTV to CAC ratio is 2.5. Payback period is CAC divided by monthly contribution margin: $18,000 divided by $750 a month is 24 months.

That is a company with attractive gross margin and unattractive unit economics: below the 3.0 ratio most investors look for, waiting two years to recover the cash it spent to win each customer.

Unit Economics in Plain English

Unit economics asks whether you make money on one customer before you ask whether you make money as a company. If a single customer never covers the cost of acquiring and serving them, adding more customers makes the problem larger, not smaller. Growth is only leverage when the unit works.

LTV to CAC Ratio and Payback Period

The two headline ratios answer different questions and both are needed. LTV to CAC measures whether the relationship is profitable over its whole life. A ratio near 1.0 means you are working for free. Around 3.0 is the common target, and well above 5.0 often signals underinvestment in growth rather than excellence.

Payback period measures how long your cash is out. A 24 month payback is a financing problem regardless of how good the lifetime ratio looks, because every new customer consumes cash today against a return spread over two years. This is why fast growing companies with strong LTV to CAC ratios still run out of money: the ratio is a profitability statement, the payback period is a cash statement, and only one of them determines whether payroll clears.

Blended vs Paid CAC and Cohort Profitability

Blended CAC divides all sales and marketing spend by all new customers, including those who arrived through word of mouth or organic search. Paid CAC divides paid spend by customers attributable to it. Blended CAC is almost always the flattering number, and the gap between the two is a useful diagnostic: if paid CAC is triple blended CAC, the business is being carried by organic demand while paid spend quietly destroys value.

Cohort analysis is the other correction. Averages blend a strong 2024 cohort with a weak 2026 one and hide the trend. Tracking contribution margin by signup cohort shows whether unit economics are improving or decaying, and whether expansion revenue in later years is offsetting churn.

Unit Economics and the Closing Motion

Unit economics is where the close shows up in the financial model. Two of its inputs move with how a deal is closed. Discounting to get a signature cuts revenue per customer and therefore contribution margin permanently, and a longer sales cycle raises CAC by consuming more selling time per win. The payback period is the input the Closing Motion changes most directly. Collecting the full contract value at Close rather than monthly over the term compresses cash payback from months to near zero, without altering the underlying margin math. Ratio Trade does exactly that: the buyer pays monthly or quarterly while the seller collects upfront. The honest tradeoff is that financing carries a cost, so contribution margin per customer decreases slightly in exchange for recovering CAC immediately instead of over two years.

Common Questions About Unit Economics

What is a good LTV to CAC ratio?

Around 3.0 is the widely used benchmark for B2B software, meaning each customer returns three times what it cost to acquire. Below 2.0 usually signals a pricing, retention, or acquisition efficiency problem. Above 5.0 often means the company could profitably spend more on growth.

Should customer success costs sit in unit economics?

Yes, in the variable cost line, to the extent they scale with the number of customers. Onboarding, support, and account management hours consumed per customer are real costs of serving that unit. Leadership salaries and platform engineering are fixed and belong outside the calculation.

Can unit economics be positive while the company loses money?

Yes, and it is the normal case for a growing company. Positive contribution margin per customer plus heavy fixed costs and acquisition spend produces losses today and profit later, provided payback periods are short enough for the cash to hold out.

Unit Economics