Blended CAC vs Paid CAC vs Fully-Loaded CAC, Defined
Blended CAC, paid CAC, and fully-loaded CAC are three genuinely different numbers, and the same company can report all three in the same month without anyone lying. Blended CAC divides total acquisition spend by every new customer, paid and free alike. Paid CAC divides only paid spend by only the customers who came in through paid. Fully-loaded CAC adds the salaries, tools, and overhead that make the ads run at all. So the real question in the blended CAC vs paid CAC debate isn't which one is right. It's which decision you're about to make.
I've watched a version of this argument play out in three different boardrooms. Growth says CAC is $42. The CFO's spreadsheet says $190. Neither of them is wrong. They're measuring different things and calling them the same word, which is how you end up with a forty-minute meeting that resolves nothing.
The three definitions, straight
Here are the formulas, spelled out so you can paste them into a cell.
| Metric | Formula | What it answers |
|---|---|---|
| Blended CAC | (All sales + marketing spend) ÷ (All new customers) | "What did the average new customer cost us this period?" |
| Paid CAC | (Paid media + paid-channel costs) ÷ (Customers sourced from paid) | "If I put another dollar into ads, roughly what does it buy?" |
| Fully-loaded CAC | (Media + salaries + tools + agencies + allocated overhead) ÷ (New customers) | "What does acquisition actually cost the business, headcount and all?" |
Note the denominators. Blended and fully-loaded both divide by all new customers. Paid CAC divides by paid customers only. That single difference is where most of the confusion lives, and it's why you can never compare your blended number to a competitor's paid number and learn anything true.
What goes in, what stays out
The messy part isn't the formulas. It's the inclusion list. Two teams using "the CAC formula" will still land on different numbers because they disagree about whether the content writer's salary counts. So let's be explicit.
| Cost item | Blended | Paid | Fully-loaded |
|---|---|---|---|
| Paid media / ad spend | ✅ | ✅ | ✅ |
| Agency & affiliate fees | ✅ | ✅ | ✅ |
| Paid creative production | ✅ | ✅ | ✅ |
| Sales & marketing salaries (+ benefits) | ⚠️ often skipped | ❌ | ✅ |
| Marketing tools & software | ⚠️ sometimes | ❌ | ✅ |
| Content / SEO / organic team cost | ⚠️ sometimes | ❌ | ✅ |
| Events & sponsorships | ✅ if paid | ✅ | ✅ |
| Allocated overhead (office, IT, admin) | ❌ | ❌ | ✅ |
| Organic / referral / word-of-mouth customers | counted in denominator | excluded from denominator | counted in denominator |
The ⚠️ rows are the ones that start fights. Most teams calling their number "blended" quietly mean "blended media spend" and leave salaries out, which makes it a fourth, unnamed metric sitting between blended and fully-loaded. If you take one thing from this piece, take this: write down your inclusion list next to the number, every time. A CAC without its inclusion list is a rumor.
Per Optifai's 2025 glossary, a properly fully-loaded figure pulls in media, salaries and benefits, tools, agencies, events, and allocated overhead. That last category, allocated overhead, is where reasonable people diverge most, so I'll come back to it in the assumptions box.
One company, three CACs, same month
This is the example I keep in my back pocket for skeptics. Eightx uses a clean version of it: a brand spends $84,000 and acquires 2,000 new customers in a month, of whom 1,200 came through paid channels.
- Blended CAC = $84,000 ÷ 2,000 = $42
- Paid CAC = $84,000 ÷ 1,200 = $70
Same spend, same month, and the number jumped 67% just by fixing the denominator to count only the customers the money actually bought. Now layer on fully-loaded. Say this team also carries $95,000/month in acquisition salaries, tools, and allocated overhead. Fully-loaded CAC = ($84,000 + $95,000) ÷ 2,000 = $89.50. Glencoyne's rule of thumb tracks this: a $50 media CAC routinely becomes $150 to $200 once you load in headcount, and Glencoyne's 2025 guide suggests grossing up salaries by roughly 1.25 to 1.4x for benefits and payroll taxes before you even start.
So the honest answer to "what's our CAC?" for this company is $42, $70, and $89.50, all correct, all useful, none interchangeable.
Which number for which decision
The mistake isn't picking the wrong CAC. It's using one CAC for every decision. Match the number to the question.
| Decision | Use this CAC | Because |
|---|---|---|
| Should I scale this ad channel? | Paid CAC (by channel) | Marginal ad dollars buy paid customers, not organic ones |
| Is the overall business efficient? | Fully-loaded CAC | The board is paying for the whole go-to-market team, not just the ads |
| Payback period & LTV:CAC ratio | Fully-loaded CAC | Anything lighter understates true recovery time |
| Quick month-over-month trend | Blended CAC | Fast, consistent, fine as long as channel mix is stable |
| Comparing yourself to a benchmark | Whatever the benchmark used | Match definitions or the comparison is noise |
Andrew Chen's old but still-correct argument is that starting from blended CAC, instead of understanding each channel's CAC, is the first mistake teams make. His point: the blended denominator counts customers you never paid for, which flatters the number and hides what happens the moment you try to buy growth. A blended CAC of $42 tells you nothing about whether ad channel #3 can absorb another $20k. Paid CAC by channel does. If your attribution can't cleanly assign customers to paid vs organic, that's a measurement problem worth fixing before you trust either number, and it usually comes down to how you're counting conversions inside your attribution windows.
Benchmarks, and why I distrust most of them
You'll want a number to compare against. Fine, but read the definition first. Benchmarkit's 2025 SaaS data puts median B2B CAC payback at about 16 months, with top-quartile teams recovering in 6 months or fewer and the bottom quartile past 24. Payback that long only makes sense on a fully-loaded CAC, so if someone quotes you a 6-month payback built on paid-media-only CAC, they've compared a light numerator to a full revenue figure and the ratio is fiction.
Here's my standing gripe: most public CAC benchmarks are survivorship-biased. The companies that report clean CAC numbers to benchmark surveys are the ones that survived long enough to have a finance team, a stable channel mix, and a reason to look good. The startups that torched their runway on a $400 paid CAC they called "$120 blended" aren't in the dataset, because they're gone. Treat industry averages as a sanity check on your own trend, not as a target to hit.
My assumptions (disagree in the comments):
- I allocate overhead to acquisition by headcount share. If 40% of the go-to-market team works on new acquisition, 40% of office/IT/admin lands in fully-loaded CAC. Some CFOs allocate by revenue instead. Both are defensible.
- I put the content and SEO team's salary in fully-loaded, not paid CAC, because organic isn't a paid channel even though it costs real money.
- I count a customer as "paid" if a paid touch was the sourcing event, not the last click. Your attribution model will move this line.
Change any of these and my numbers move. That's the point. Publish your assumptions with your number.
Practitioner's checklist
You don't need a data warehouse to get this right. You need discipline about three things.
- Fix the denominator. Blended and fully-loaded divide by all new customers; paid divides by paid-sourced customers only. Never cross the wires.
- Attach the inclusion list. State what's in the numerator every time you report a CAC. A CFO I worked with wouldn't approve a single budget line until the CAC in the deck carried its inclusion footnote, and honestly, she was right to.
- Pick the CAC per decision. Paid-by-channel for scaling, fully-loaded for efficiency and payback, blended for a fast trend line.
Do that and the boardroom fight goes away, because everyone's finally arguing about the same number. If you want the loaded version wired into a payback and LTV:CAC view, I laid out the full sheet in the unit economics dashboard template.
FAQ
Is blended CAC or paid CAC "better"? Neither. Paid CAC tells you what marginal ad spend buys; blended CAC tells you the average cost across all new customers. Use paid to decide whether to scale a channel, blended for a quick trend.
Should CAC include salaries? For a true picture, yes, that's fully-loaded CAC. For a fast channel-scaling decision, no, use paid CAC. Just label which one you're showing.
Why is my blended CAC so much lower than paid CAC? Because organic, referral, and word-of-mouth customers sit in the blended denominator at zero cost, dragging the average down. The bigger the gap, the more your growth leans on channels you don't pay for.
Which CAC do I use for payback period? Fully-loaded, always. Payback and LTV:CAC built on paid-media-only CAC understate what acquisition actually costs and make the business look healthier than it is.