SaaS Unit Economics: CAC, LTV and Payback Worked Through

Use these definitions and keep them the same each period:

• CAC: total sales and marketing spend for a period divided by new customers won in that period. Include salaries, commissions, tools, programs and a share of overhead for the teams involved.
• Gross-margin contribution per customer per month: average monthly revenue per account times gross margin.
• CAC payback (months): CAC divided by gross-margin contribution per customer per month.
• LTV: gross-margin contribution per month divided by monthly churn rate.
• LTV to CAC ratio: LTV divided by CAC.

For example, say you spent $150,000 on sales and marketing in a quarter and won 30 customers, so CAC is $5,000. Say average revenue is $500 a month at an 80 percent gross margin, so contribution is $400 a month. Payback in that case is $5,000 divided by $400, or 12.5 months, if your numbers look like these. Say monthly churn is two percent: LTV is $400 divided by 0.02, or $20,000, and LTV to CAC is 4.0.

Use benchmarks as a reference point, not a target. The 2026 Aleph and Benchmarkit report on FY2025 data found median CAC payback of 16 months, with the best quartile at 6 months or less and the worst at 24 months or more¹. Payback varies strongly with contract size, so compare with companies that sell at a similar price point.

Margin matters because blended figures can hide a lot. Benchmarkit's 2025 report put median subscription gross margin at 81 percent and services gross margin at 30 percent². If your revenue mix includes services, compute payback on the margin of what the customer actually buys, not on the 80-percent-plus figure for the software alone.

Your own trend is often more useful than the benchmark. If payback was 10 months a year ago and is 14 now, something changed: channel mix, pricing, sales productivity or discounting. Find out which.

These are the ones that most often flatter the numbers:

• Using revenue instead of gross margin. Payback and LTV on revenue can overstate value by a wide margin.
• Leaving costs out of CAC. Sales salaries, commissions, marketing headcount, agency fees and tools all belong.
• Blending paid and organic customers. Blended CAC hides what it costs to buy growth. Track paid CAC separately.
• Ignoring the lag. Spend in one quarter often produces customers a quarter or two later, so match spend to the customers it produced.
• Estimating churn from too few customers. A couple of early cancellations swing the rate. Use cohorts and wait for enough data.
• Letting LTV run forever. A two percent monthly churn implies a 50-month average life. Many analysts cap the lifetime at a few years to stay conservative.
• Excluding expansion or contraction. If customers grow or shrink, average revenue changes over the lifetime.

Set up one tab per cohort or channel, and work through these steps:

1. List monthly sales and marketing spend by category from your general ledger.
2. List new customers by month and by acquisition channel.
3. Shift spend forward by your typical sales cycle so it lines up with the customers it produced.
4. Compute CAC for each period and channel.
5. Pull revenue per account and gross margin from your income statement, and take out costs that belong in cost of goods sold, such as hosting and customer support.
6. Compute payback and LTV, then chart them over time.

Compare the results with the ranges in your financial model, and use the CAC payback period calculator guide if you want a deeper look at payback. A consistent chart of accounts makes step 1 far easier.

Use them to make three decisions. First, which channels earn their spend: compare payback by channel and shift budget toward the shorter ones, while remembering that some channels have a longer sales cycle. Second, whether pricing or packaging needs work: if payback is long because average revenue is low, the fix may be price, not acquisition. Third, how much you can afford to grow: long payback means each new customer ties up cash for many months, so growth needs funding.

Track the numbers monthly against plan in your budget vs actual report, and revisit definitions whenever your model changes. A planning tool such as Mosaic or Jirav can keep the inputs connected to your accounting data; confirm in a demo how each handles cohorts and channel-level reporting, and compare them in Jirav vs Cube vs Mosaic. For services-heavy models, the break-even analysis for service businesses is a useful companion.