$0.02 CAC: the full arithmetic, and what it does not mean
My headline number, taken apart honestly. What blended means, what was organic, which parts would repeat for you and which would not.
the short answer: i scaled ZuAI from 10,000 to 2,000,000 users in eleven months at a $0.02 blended cost of acquisition, on roughly $300k a month of ad spend. that number is real and it is also the most misleading thing on my site if you do not know what sits behind it. here is the arithmetic and the honest limits.
What “blended” actually means
blended CAC is total acquisition spend divided by total new users, including the ones who arrived for free.
that is a genuinely useful number for a founder, because it tells you what growth cost you in total. it is a bad number for comparing operators, because a large organic base makes any paid effort look cheaper than it was.
so the honest framing: $0.02 blended does not mean i bought two million users at two cents each. it means the mix of paid and organic, taken together, cost that on average.
What made the organic side work
three things, in rough order of contribution.
the product was shareable in a specific way. students showed each other results. that is a category advantage, not a marketing achievement, and if your product does not have it you should discount everything here accordingly.
reddit seeding brought users who stayed. never the biggest volume channel. consistently the best retention, and retention is what pulls a blended number down over time, because retained users keep counting in the denominator while you stop paying for them.
the creative itself travelled. raw phone-shot UGC gets reposted in a way that studio work does not. some of the paid creative earned organic distribution, which is the cheapest thing that can happen to an ad.
What made the paid side work
volume, and an ordering rule.
only about 5% of meta creatives become winners. the published production benchmark is roughly one new ad per $3,000 of monthly spend, which at $300k a month predicts about 100 ads. i ran 150+, about 1.5x that rate. the industry data says brands testing ten or more concepts a month see 31% lower cost per acquisition than those testing fewer than five, from an analysis of over 500,000 ads and $1B+ in spend, and that is the whole mechanism.
the ordering rule: paid budget only followed creatives that had already proven themselves. paid was the amplifier, never the discovery mechanism. run it the other way and your cost per acquisition rises as you scale, because you are buying reach for things you have not verified.
What would not repeat for you
being straight about this because it is the part that matters if you are deciding whether to hire me.
the category. an AI study app aimed at students has a large, reachable, highly social audience. a B2B compliance tool does not. the method transfers, the number does not.
the moment. consumer AI in that window had novelty on its side. novelty converts, and it also churns, which is a separate problem i wrote about in why your AI app loses nine in ten subscribers before the first renewal.
the spend level. $300k a month buys enough tests to find winners quickly. at $10k a month the same method works but the learning takes far longer, and below roughly that level most consumer channels cannot produce a signal fast enough to be worth paying someone to run.
the starting base. we started at 10,000 users, not zero. there was something to learn from.
What would repeat
the creative arithmetic. the kill discipline. the rule that paid follows proof. the fact that a channel bringing users who stay is worth more than a cheaper channel bringing users who leave.
those are not category-specific and they are the actual transferable content of the case.
Why I publish the limits
because the alternative is a headline number that does its job in a search result and then disappoints in a first meeting.
if the arithmetic above makes you think your situation is different, it probably is, and the useful conversation is about what your number could realistically be rather than what mine was. the full engagement write-up is in the ZuAI case study.
if you want that conversation, let’s talk.
sources: ZuAI figures from internal dashboards during the engagement; ZuAI has since rebranded to Professor Curious · adliftr analysis of 500,000+ meta ads and $1B+ spend · published 2026 meta creative production benchmarks.