CAC Calculator — Customer Acquisition Cost

Background.

A founder tells her board that each new customer cost $150 last quarter. A week later her head of growth tells investors the figure is $160. Both are right. The founder divided all $60,000 of acquisition spend by all 400 new customers; the growth lead divided the $40,000 spent on paid channels by the 250 customers those channels brought in. Customer acquisition cost is a ratio with no official definition, so the first thing to ask of any CAC figure is what went into the top and the bottom of it.

No accounting standard defines CAC and no regulator prescribes it, and the definitions people cite most often disagree on scope. David Skok divides the sales and marketing expense line by the number of new customers. Andreessen Horowitz calls it "the full cost of acquiring users, stated on a per user basis" and insists on including referral fees, credits and acquisition discounts, which usually sit outside that expense line. Bessemer Venture Partners reaches wider still, counting sales compensation, content and brand marketing, demand generation and the customer-success cost related to sales. One company can produce three different CACs from the same books. That is why the calculator prints the spend and the customer count it actually divided beside the answer.

The second choice is blended or paid. Blended CAC spreads everything you spent over everyone you won, including customers who arrived through word of mouth. Paid CAC looks only at paid channels and the customers they produced, which makes it the better guide to what another dollar of advertising will buy. Andreessen Horowitz's illustration: if half your users cost $100 each through paid marketing and the other half arrive free, paid CAC is $100 and blended CAC is $50. Blended is not always the smaller figure, though; it can land above paid CAC when brand and content spend brings in few customers.

On its own, a CAC figure decides very little. $150 is cheap for a contract worth tens of thousands a year and ruinous for a $9-a-month app. It becomes a decision when you set it against what a customer is worth, as a lifetime-value ratio or as the months of gross profit it takes to earn the cost back.

What is cac calculator?

Customer acquisition cost is the money spent winning new customers during a period divided by the number of new paying customers won in that same period. It is an average over the period, not the cost of the next customer, which is usually higher as cheaper channels fill up. It is also not the cost per acquisition (CPA) an ad platform reports: CPA counts whatever conversion event the campaign was set to optimise, often a lead or a trial, inside one ad account, whereas CAC counts paying customers across all channels. CAC is not a GAAP measure. Companies that publish it choose their own scope, which is why the method matters as much as the number.

How to use this calculator.

1. 01Fix the period first: a month suits self-serve products with short buying cycles, a quarter suits anything sold by a sales team. Every figure you enter must come from the same window.
2. 02Choose Which CAC do you want? Blended answers what growth cost on average; paid answers what it costs to buy one more customer through advertising. For an investor update, run both and label each.
3. 03Enter Paid-channel acquisition spend: media and ad spend, agency fees, affiliate and referral bounties, acquisition discounts and credits, and the loaded cost of salespeople who work only paid leads.
4. 04Enter Other acquisition cost: brand and content marketing, PR, events, marketing tools and inbound sales staff. Decide once whether to follow Bessemer and include the sales-related share of customer success, then keep that choice every period.
5. 05Enter New customers from paid channels and New customers from organic channels, counting customers who started paying in the period, not signups, trials or leads. If you cannot split customers by channel, put them all in the paid field and read only the blended result, since the paid figure would then divide paid spend by every customer.
6. 06Check the numerator and denominator shown with the result, then take the CAC to the LTV:CAC ratio and CAC payback calculators, where it turns into a spending decision.

The formula.

With S_paid for paid-channel spend, S_other for other acquisition cost, N_paid for paid-attributed customers and N_organic for organic customers:

Blended CAC = (S_paid + S_other) ÷ (N_paid + N_organic) Paid CAC = S_paid ÷ N_paid Organic share = N_organic ÷ (N_paid + N_organic) × 100

Paid CAC ignores S_other and organic customers entirely. Blended CAC can be rewritten as a customer-weighted average of two rates: paid CAC, weighted by paid customers, and the unattributed spend per organic customer, S_other ÷ N_organic, weighted by organic customers. In the worked example those rates are $160 and 20,000 ÷ 150 = $133.33, and the weighted average of 250 customers at $160 and 150 at $133.33 is $150. Blended CAC therefore falls below paid CAC exactly when the unattributed spend per organic customer is lower than paid CAC, and rises above it when that spend is higher. Bear in mind that pairing brand spend with organic customers is a bookkeeping view; brand work also helps paid ads convert.

Zero spend is accepted, because a quarter won entirely by word of mouth really does have a CAC of $0. Zero customers is not: cost per customer is undefined with nobody to divide by, and the paid basis likewise needs at least one paid-attributed customer.

Because CAC is an average, it understates what growth costs at the margin. If another $10,000 of paid spend on top of the example's $40,000 brought in 40 more customers, those customers would cost $250 each, yet the average paid CAC would only rise from $160 to $172.41. Rising average CAC usually signals that the marginal figure has been climbing for a while.

Timing is the other source of distortion. In a business with a long sales cycle, the customers who close this quarter were often worked on last quarter, so some teams pair each period's new customers with the previous period's spend. Either approach is defensible if you state it and apply it consistently.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Andreessen Horowitz — Jordan, J., Hariharan, A., Chen, F., & Kasireddy, P. (21 August 2015). "16 Startup Metrics." Metric 7 defines CAC as "the full cost of acquiring users, stated on a per user basis" and gives the blended vs paid distinction and the $100/$50 illustration used on this page. Open web, retrieved 2026-07-29.
2. [2]Skok, D. "SaaS Metrics 2.0 — Detailed Definitions," forEntrepreneurs.com. Gives CAC as "Sales & Marketing Expenses / Number of New Customers Acquired" and notes the distortion in early-stage companies. Undated revision, current as retrieved 2026-07-29.
3. [3]Bessemer Venture Partners — D'Onofrio, M. "Scaling to $100 Million" (updated 2024 edition, PDF). Source of the wider S&M scope quoted on this page ("sales expenses, sales compensation, content and brand marketing, demand generation, and customer success expenses related to sales") and of the 3x CLTV/CAC and segment payback benchmarks. Open web PDF, retrieved 2026-07-29.
4. [4]U.S. Securities and Exchange Commission — "Commission Guidance on Management's Discussion and Analysis of Financial Condition and Results of Operations," Release Nos. 33-10751; 34-88094; FR-87, issued 30 January 2020, effective 25 February 2020. Section on Key Performance Indicators and Metrics requires "a clear definition of the metric and how it is calculated," a statement of why it is useful and how management uses it, and disclosure of any change in the method of calculation. Federal Register text via GovInfo (sec.gov blocks automated retrieval); retrieved 2026-07-29.
5. [5]Gupta, S., Lehmann, D. R., & Stuart, J. A. (2004). "Valuing Customers." Journal of Marketing Research, 41(1), 7–18. Cohort model equations (3) and (6) subtract acquisition cost c_k per customer at acquisition; Table 4 reports acquisition-cost elasticity of 0.02–0.3 against retention elasticity of 2.45–6.75. Author copy hosted by Columbia Business School; retrieved 2026-07-29.
6. [6]Financial Accounting Standards Board — Accounting Standards Codification Topic 340-40, "Other Assets and Deferred Costs — Contracts with Customers," paragraphs 340-40-25-1 to 25-4 (added by ASU 2014-09, Revenue from Contracts with Customers (Topic 606)). Requires incremental costs of obtaining a contract, such as a sales commission, to be recognised as an asset when recovery is expected. Bibliographic citation only: the Codification is behind a free-registration wall, so no verbatim text is attributed to the link.