CAC & Payback
Customer acquisition cost per channel and blended, months to pay it back from monthly gross profit per customer, and a simple LTV and LTV:CAC from your churn.
What each customer costs to win by channel, how many months of gross profit repay it, and how that compares with lifetime value — all from your own spend, ARPA, margin and churn.
Example: Ads 12,000 for 80 customers → CAC 150; at 90 per month and 70 % margin each customer yields 63 a month, so payback is 2.38 months; with 3 % monthly churn LTV is 2,100.
What a customer costs,
and how long until they have paid for it.
The definitions, why payback uses gross profit rather than revenue, what the simple LTV formula assumes, and what it does not.
CAC and payback
CAC is the spend on a channel divided by the new customers it won in the same period — put in whatever you count as acquisition spend (media, agency, sales salaries) and be consistent across channels. The blended figure divides total spend by total customers, not the average of the channel figures. Payback is CAC divided by the monthly gross profit a customer brings: monthly revenue per account (ARPA) times gross margin. It uses gross profit, not revenue, because only the margin is available to repay the acquisition cost.
LTV and the ratio
With a monthly churn rate entered, the page computes the simple lifetime value: monthly gross profit ÷ churn, which equals gross profit × expected lifetime (1 ÷ churn months). It is undiscounted, assumes constant churn and constant ARPA, and counts no expansion revenue — a first estimate, not a valuation. LTV:CAC divides that by CAC. The page does not tell you what ratio is "good"; benchmarks depend on sector, growth rate and cost of capital, and belong to your own judgement.
What the tool does not do
No cohorts, discounting, attribution between channels, or trial-to-paid conversion; a channel that assists another's conversions is under-counted here. Enter figures for one period and one customer definition. Nothing you enter leaves the browser; the same four anonymous usage counts as the rest of the site apply.