What is Customer Acquisition Cost (CAC)?

CAC is the average amount you spend on sales and marketing to win one new paying customer. The formula is CAC = total marketing and sales spend / number of new customers acquired in the same period. A lower CAC relative to the value a customer generates means your growth is more efficient and sustainable.

How is blended CAC different from per-channel CAC?

Blended CAC aggregates every channel into one figure (total spend / total customers). Per-channel CAC isolates each source — e.g. Google Ads, Meta, email — so you can compare efficiency and reallocate budget toward channels that acquire customers most cheaply or most profitably.

What is a good LTV:CAC ratio?

The industry benchmark is 3:1 — each customer should generate at least three times what it costs to acquire them. A ratio below 1:1 means you lose money on every customer. Between 1:1 and 3:1 is marginal or acceptable depending on growth stage. Ratios above 5:1 may indicate you are under-spending on acquisition and leaving growth on the table.

How is LTV calculated from ARPU, margin and churn?

The standard SaaS formula is LTV = (monthly ARPU x gross margin %) / monthly churn %. For example: ARPU = $40, gross margin = 70%, monthly churn = 5% gives LTV = (40 x 0.70) / 0.05 = $560. This model assumes a constant churn rate and is a useful approximation — cohort analysis gives a more precise figure if you have the data.

What does payback period mean?

Payback period = CAC / (monthly ARPU x gross margin). It tells you how many months of gross profit are needed to recover the cost of acquiring a customer. A 12-month payback is common for SaaS; below 6 months is strong; above 18 months may stress cash flow, especially if you are pre-revenue or growing fast.

Should I include salaries in CAC?

Best practice is to include all sales and marketing costs — ad spend, agency fees, tool subscriptions, and the salaries of everyone in sales and marketing — divided by the number of new customers. Excluding salaries understates your true CAC. For a quick benchmark, ad-spend-only CAC is fine; for financial planning and investor decks, use fully-loaded CAC.

Customer Acquisition Cost (CAC) Calculator

The Customer Acquisition Cost (CAC) Calculator tells you exactly how much you spend, on average, to win one new paying customer — broken down by marketing channel and benchmarked against the lifetime value of those customers. Whether you run paid search, paid social, email campaigns, or all three, this tool gives you the single number that determines whether your growth engine is actually profitable.

Why CAC matters

CAC is the denominator in the most important ratio in growth marketing: LTV:CAC. If a customer is worth $480 over their lifetime and it costs you $40 to acquire them, your ratio is 12:1 — exceptional. If it costs $500 to acquire a $480 customer, you are burning money on every signup no matter how fast you grow. Investors, CFOs, and growth leads all watch this ratio closely. A ratio of 3:1 or above is the widely-cited benchmark for a healthy, scalable acquisition model.

How the calculator works

Step 1 — enter your channels. Add a row for each marketing channel (Google Ads, Meta, LinkedIn, referral, email, etc.). Enter the total ad spend and the number of new customers that channel generated in the same period (usually a calendar month or quarter).

Step 2 — blended CAC. The tool divides total spend by total new customers:

CAC = total marketing spend / new customers acquired

Step 3 — per-channel CAC and spend share. The breakdown table shows each channel’s individual CAC alongside its percentage of your total budget, so you can see at a glance which channels deliver customers cheaply and which are draining budget inefficiently.

Step 4 — LTV and the LTV:CAC ratio (optional). Paste in a known LTV figure, or tick the checkbox to derive it from first principles using the standard SaaS formula:

LTV = (monthly ARPU × gross margin %) / monthly churn %

For example: monthly ARPU = $40, gross margin = 70%, monthly churn = 5% yields LTV = (40 × 0.70) / 0.05 = $560.

Step 5 — payback period. When ARPU-mode is on, the tool also computes:

Payback (months) = CAC / (monthly ARPU × gross margin)

This shows how many months of gross profit it takes to recoup acquisition spend — a critical metric for cash-flow planning and fundraising.

Worked example

A SaaS startup runs three paid channels in May:

Channel	Spend	New customers	CAC
Google Ads	$5,000	120	$41.67
Meta Ads	$3,000	60	$50.00
LinkedIn	$2,000	20	$100.00
Total	$10,000	200	$50.00

Blended CAC = $10,000 / 200 = $50.00.

Monthly ARPU = $40, gross margin = 70%, churn = 5%.

LTV = (40 × 0.70) / 0.05 = $560.

LTV:CAC = 560 / 50 = 11.2× — excellent.

Payback = 50 / (40 × 0.70) = 1.79 months.

The LinkedIn channel has a CAC of $100 — double the blended average. With LTV of $560 its ratio is still 5.6×, so it is profitable, but budget might be better deployed into Google Ads (12.5× ratio) before scaling LinkedIn further.

Formula reference

CAC = total sales and marketing spend / new customers acquired
LTV = (monthly ARPU × gross margin %) / monthly churn %
LTV:CAC ratio = LTV / CAC
Payback period = CAC / (monthly ARPU × gross margin %)

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