Free tool — runs in your browser, no account to start
Is My Marketing Working?
Payback in months first, because it needs no guess about the future. Then LTV:CAC as a range, and the incrementality question no ratio can answer.
Is my marketing actually working?
Five questions, about two minutes. Payback in months first — the number that doesn't depend on any guess about the future — then what it's worth over time, shown as a range because nobody can honestly know that one exactly.
Free, and no card. One question asks for a guess on purpose — you'll give a low and a high, not a single invented number.
See how it works
Informational only — not audit, attest, legal, tax, or investment advice. This is arithmetic on the figures you enter; it is only as good as they are.
A ratio is only as honest as the guess behind it
Most cost-per-acquisition math stops at a ratio — LTV:CAC, with three-to-one held up as some kind of law. The ratio hides two things: whether the business can actually survive the wait to collect that lifetime value, and how much of the ratio is really just an assumption about how long a customer sticks around.
This tool puts payback first because it doesn’t need that assumption — it’s just what a customer cost, divided by what one is worth per month. The ratio comes after, as a range built from your own low and high guess about retention, so the uncertainty is visible instead of buried inside one confident-looking number.
It also names the question a ratio can never answer on its own: whether these customers would have shown up anyway. That takes an actual test to find out, not a formula — so this tool explains the test instead of pretending to run it.
Worked example: A dental membership plan's payback holds at under two months no matter how the retention guess moves. The ratio next to it swings from 5:1 to 36:1 on the same guess →
Two Rivers Dental runs its membership incentive through the two-minute version of the marketing math, nine months in. Payback stays under two months whether the honest cost is $10 or the fully-loaded $27. The LTV:CAC ratio beside it swings from under 5:1 to over 36:1 depending on a guess nobody has tested yet — which is exactly the number the practice sent upstairs for a harder look.
Frequently asked questions
Why does payback come before the LTV:CAC ratio?
Payback needs nothing but what a customer already cost and what one is worth per month — no guess about the future required, so it's the one number here that's exact. LTV:CAC needs a retention assumption nobody can honestly make, so it's shown beneath, as a range, rather than leading with a number that looks more certain than it is.
Why do I have to give a low and a high guess for retention, instead of just one number?
Because a single figure would look precise and isn't. Retention is the one assumption in this tool nobody can know in advance, so it's asked for as a range from the start — not offered only if you skip a straight question. Both ends get computed in full, and the swing between them is exactly the lesson: a wide swing means the ratio isn't trustworthy yet, a narrow one means it barely matters.
What is incrementality, and why doesn't this tool compute it?
It's the question of whether a customer would have bought anyway, without the marketing. It's the most honest question in marketing and the one almost nobody asks, because answering it takes an actual test — a holdout, where a comparable slice of the business sees none of the spend for a while and gets compared to everyone else. Nothing in this tool measures that, so nothing in it invents a score for it. The results page explains the test instead.
What CAC figure should I use?
Your best one. If you've run True Cost Per Customer, use the fully loaded figure from there — it's the honest one. If all you have is ad spend divided by customers won, that works too, but understands you're probably understating the real cost.
Do I need an account?
No. Payback, the LTV:CAC range and the incrementality explanation are all free with no email wall. Signing in only keeps the result so a later run can show you what moved.