Free tool
Max CAC Calculator
What can a new customer cost?
A margin-based ceiling for your acquisition spend, translated into a max cost per SQL and per lead.
How it works
Pick your revenue model. One-off revenue (projects) or recurring revenue (subscriptions and retainers): that choice sets the formula. Enter your deal value or monthly revenue, your gross margin and how long or how often a customer keeps buying, directly or derived from your churn.
Read your max CAC. The tool calculates the lifetime gross margin of one customer and applies an adjustable rule of thumb: the share of that margin that may go to acquisition. In recurring mode you also see your payback period, with a warning above 12 months.
Translate it into your funnel. Using your conversion rates, the ceiling becomes a max cost per SQL and per lead. Put those next to what an SQL costs you today in the Lead Gen Budget Calculator, and check with the Pipeline Coverage Calculator whether there is enough pipeline behind it.
What’s behind the numbers
The formulas are deliberately simple and checkable. Customer value = deal value x gross margin x repeat purchase factor, or LTV = monthly revenue x margin x customer lifetime. Max CAC = an adjustable share of that lifetime margin. No black box, no invented weightings.
The rules of thumb are stated as rules of thumb. A 30% CAC share of lifetime margin is a conservative, defensible default. The 3:1 LTV:CAC ratio is the widely used SaaS benchmark, and it is the same criterion: 3:1 corresponds to 33% of lifetime margin. The payback warning above 12 months is a guideline, not a law. Everything is adjustable to your own situation.
What the tool deliberately does not do: claim channel-specific CAC benchmarks (there is no defensible source per sector-channel combination) or take a position in the blended-versus-paid CAC debate. Your numbers in, an honest ceiling out.
FAQ
What is CAC, and what is a max CAC?
CAC is your customer acquisition cost: everything you spend to win one new customer, from media budget to sales time. Your max CAC is the ceiling: what one customer may cost at most while staying profitable. This tool calculates that ceiling as an adjustable share of the lifetime gross margin a customer brings.
Why calculate on margin instead of revenue?
Acquisition is paid out of margin, not out of revenue. A 15,000 euro deal at 60% gross margin leaves 9,000 euro to cover acquisition, delivery overhead and profit. Whoever calculates on revenue systematically overestimates what a customer may cost. That is why the tool asks for your gross margin first.
What do max cost per SQL and per lead mean?
They translate the ceiling to where you actually buy: campaigns deliver leads and SQLs, not customers. At a 25% SQL-to-client rate you need four SQLs per customer, so one SQL may cost a quarter of your max CAC. Compare those ceilings with what an SQL or lead costs you today, for example in the Lead Gen Budget Calculator.
Is the tool free and do I need an account?
Free, no account needed. All results are visible right away. Want to keep your scenario? Download it as a PDF report with your email address.
More free tools: Lead Gen Budget Calculator · Pipeline Coverage Calculator · Belgian TAM Calculator · all tools
Knowing your max CAC is the start.
Getting your real CAC under that ceiling, with the right channels, funnel and pricing, that is what I help B2B teams with.