CAC Calculator
Three numbers get called CAC and they differ by a factor of two on the same business. This CAC calculator shows all three and says which one the decision needs.
Blended CAC
- Blended CAC $75,000.00 of total acquisition cost over 120 customers. This is the figure to report, because it is the only one that accounts for every dollar spent.
- $625.00
- Paid CAC (media only) Ad spend over the customers the ads produced. It is the figure platforms report and it excludes every salary, so it is always the flattering one.
- $533.33
- Paid CAC (fully loaded) All $75,000.00 over the 75 customers paid acquisition produced. This is the honest marginal figure: the 45 organic customers would have arrived anyway and are subsidizing the blended number.
- $1,000.00
- Organic share 45 of 120 customers arrived without paid acquisition. That is a large subsidy, and it means blended CAC understates what growth actually costs at the margin by 60%.
- 37.5%
- CAC payback period $625.00 recovered at $64.00 of gross profit a month. Under 12 months is healthy for a business selling monthly; over 18 means growth consumes cash faster than it generates it.
- 9.8 months
- Gross profit per customer per month $80.00 of revenue at a 80% gross margin. CAC is paid in cash, so this, not revenue, is what pays it back.
- $64.00
- What the next 10 customers cost At the marginal rate of $1,000.00, not the blended rate of $625.00. Budgeting growth at the blended figure is how acquisition targets get set 60% too low.
- $10,000.00
| Figure | Spend counted | Customers counted | CAC |
|---|---|---|---|
| Paid, media only | $40,000.00 | 75 | $533.33 |
| Blended | $75,000.00 | 120 | $625.00 |
| Paid, fully loaded | $75,000.00 | 75 | $1,000.00 |
- A CAC quoted without saying which of these three it is cannot be compared with anyone else's, and frequently cannot be compared with the same company's figure from last quarter.
- All three assume the spend in a period produced the customers in that period. Where the sales cycle is long the two do not line up, and CAC computed on a short window will swing wildly for reasons that have nothing to do with efficiency.
How the CAC Calculator works
Customer acquisition cost is what you paid, divided by what you got. The division is trivial. The difficulty is that there are three defensible answers depending on what goes above and below the line, and they routinely differ by a factor of two on the same set of books.
Blended CAC is all sales and marketing cost divided by all new customers. $75,000 over 120 customers is $625. It is the figure to report externally, because it is the only one that accounts for every dollar: no spend is excluded and no customer is excluded.
Paid CAC, media only is advertising spend divided by the customers advertising produced. $40,000 over 75 is $533. This is what the ad platforms report, and it leaves out every salary, every tool and every content hire. It is always the smallest of the three and it is the one most often quoted without qualification.
Paid CAC, fully loaded apportions the whole cost to the customers paid acquisition actually produced. $75,000 over 75 is $1,000. The reasoning is that the salesperson who closed a paid lead is part of what that lead cost, and the organic customers would have arrived with the campaigns switched off.
That last figure is the one most decisions need, and it is the one almost nobody computes. The reason it matters is marginal cost. If 45 of your 120 customers were going to arrive regardless, they are subsidizing the blended number, and the next customer you buy costs $1,000, not $625. A growth plan budgeted at the blended rate is underfunded by 60% before it starts, and the shortfall only becomes visible after the money is committed.
The organic share is what drives the gap. At 0% organic all three figures converge. At 50% organic the fully loaded paid figure is double the blended one. This is also why CAC appears to rise when a company starts spending seriously: the organic base is fixed, so as paid volume grows it dilutes a subsidy that was always there, and a number that was quietly flattered stops being flattered.
Two things to hold the figure lightly for. The first is attribution: "came from paid" is a judgment made by a tracking system using a last-click or view-through model, and it systematically claims customers who would have converted anyway. The honest test is incremental (what happens to volume when a channel is switched off), and the gap between attributed and incremental is usually large and always in the same direction.
The second is timing. Every version of this calculation assumes the spend in a period produced the customers in that period. Where the sales cycle runs to months, it did not. Computing CAC on a monthly window for a business with a ninety-day cycle produces a number that swings with the calendar rather than with efficiency, and reacting to those swings is how acquisition budgets get cut in the quarter the pipeline was working.
CAC on its own is not a verdict. It is half of a ratio, and the other half is lifetime value: a $1,000 CAC is excellent against a $5,000 LTV and ruinous against an $800 one.
CAC Calculator FAQ
What is included in customer acquisition cost?
All sales and marketing cost over the period: advertising, salaries and commission for sales and marketing staff, agencies, content, events and the tooling they use. What is excluded is product, engineering, support and general overhead. The common error is counting only advertising, which produces a figure that can be half the real one.
What is the difference between blended CAC and paid CAC?
Blended divides all acquisition cost by all new customers, including those who arrived organically. Paid divides advertising cost by the customers advertising produced. Blended is the honest total; paid describes a channel. The number most decisions need is a third one (all cost over paid-sourced customers only), because that is what the next customer will cost.
What is a good CAC payback period?
Under 12 months is generally healthy for a business billing monthly, and under 6 is strong. Beyond 18 months growth consumes cash faster than it produces it, so the faster you grow the more financing you need. Payback is a cash question and is distinct from LTV:CAC, which is a profitability one. A business can pass the second and fail the first.
Why did our CAC go up after we increased spend?
Usually for two reasons at once. Paid channels saturate, so later dollars reach a less interested audience than earlier ones. And the organic base is roughly fixed, so as paid volume grows the subsidy it was providing to the blended figure gets diluted. The second effect makes CAC appear to rise even when every channel is performing exactly as it did.