The same £1,000 CAC pays back in 5.0 months on revenue and 6.25 on gross margin. Only one of those is real
CAC, Payback and LTV Calculator
CAC, payback in gross-margin months and lifetime value from five inputs, with the flattering revenue basis shown alongside so you know both numbers.
CAC, Payback and LTV Calculator
Acquisition cost, payback in months on the gross-margin basis, and lifetime value without the flattering shortcuts.
The conventions, stated
Payback runs on GROSS-MARGIN pounds: the demo's £1,000 CAC against £160 of monthly margin is 6.25 months. On revenue it would flatter to 5.0, and the flattering version is the one that gets quoted.
LTV is ARPA times gross margin over monthly revenue churn. Using logo churn, or skipping the margin, inflates it, and diligence recomputes it the honest way.
The healthy shapes, roughly: payback under 12 months for SMB SaaS, LTV to CAC above 3. The demo runs 6.25 months and 7.3, which is why it can afford to grow.
Take the workbook
CAC, payback and LTV in Excel with both conventions shown side by side, so the flattering version is visible next to the honest one.
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