CAC Calculator

This CAC calculator turns two figures into the number a marketing budget is usually judged by: what it cost, all in, to win one customer. Enter the total acquisition cost — the ad spend plus the tools, agency fees and salaries that produced the customers — and the number of new customers it produced, and the card returns the customer acquisition cost together with the readings that make it comparable: how many customers $1,000 buys at this rate, what 100 customers cost, and what a push for 1,000 customers would require. Fill in the optional LTV field and three more rows appear: the LTV : CAC ratio, the value left per customer after CAC, and CAC as a share of LTV.

A customer acquisition cost calculator is only half a reading on its own. The number becomes a decision when it is set next to what a customer is worth: the common reference guideline is an LTV : CAC of at least 3× — roughly, the customer pays back what it cost to win them within a year — but that is a rule of thumb drawn from how subscription businesses are usually financed, not a law. A high CAC can be a good investment when customers stay for years, and a low CAC can be a bad one when they leave in a month.

What Customer Acquisition Cost Measures

Customer acquisition cost is the average all-in cost of winning one customer over a period: everything spent on acquisition during that period, divided by the number of new customers it produced. The definition sounds simple and is easy to flatter, because the interesting question is what “everything spent” contains — and that decision is what makes two CAC figures for the same business disagree.

What Belongs in Total Acquisition Cost

What belongs in the numerator: the media you bought (search, social, display, print, transit), the tools you pay for to run acquisition (email platform, CRM, landing pages, analytics), any agency or freelancer fees, the salaries and commissions of the people whose job is acquisition, and the discounts or promotions used to win the customer — a first-month discount is a cost of acquisition even though it never appears on an ad invoice.

What is often left out: salaries and commissions, because they sit in the payroll budget rather than the marketing one; discounts, which get recorded as reduced revenue instead of as a cost; and the creative production, content and selling time that nobody invoices. That is why the CAC in an ad platform’s report and the CAC on this page can differ by a factor of two or more: one counts media, the other counts customers. The figure is worth quoting with its definition attached, because “CAC of $50 including salaries” and “CAC of $20 of media spend” can both be true of the same month.

CAC, CPA and Cost per Acquisition: What Is the Difference

CPA — cost per acquisition, the figure people mean when they search for a cost per acquisition calculator — is the narrower measure: media spend divided by the conversions that media produced. CAC divides a wider cost by a different count. Both differences matter. The numerator: CPA usually counts only the ad spend, so salaries, tooling, agency fees and discounts are missing from it. The denominator: a conversion is whatever the platform could observe — a click, a lead, a sign-up, an order — while a new customer is a person who bought, possibly through a different channel than the one that got the credit. Use the CPA calculator to judge a campaign, and CAC to judge whether the cost of winning customers is sustainable for the business at all.

The CAC Formula and the Rows Around It

The CAC formula is a single division:

\[ \text{CAC} = \frac{\text{total acquisition cost}}{\text{new customers}} \]

Total acquisition cost is the numerator and new customers is the denominator — the count that has to be greater than zero, because with nobody to divide by, the cost per customer is undefined rather than zero. Every other row on the card is this one number read in different units: dollars per customer, customers per $1,000, and — once an LTV is supplied — the customer’s value measured against their cost.

\[ \text{Customers acquired per } \$1{,}000 = \frac{1000}{\text{CAC}} \]

\[ \text{Cost per 100 customers} = \text{CAC} \times 100 \]

\[ \text{Spend needed for } 1{,}000 \text{ customers} = \text{CAC} \times 1000 \]

\[ \text{LTV} : \text{CAC} = \frac{\text{LTV}}{\text{CAC}} \]

\[ \text{Value left per customer after CAC} = \text{LTV} – \text{CAC} \]

\[ \text{CAC as a share of LTV} = \frac{\text{CAC}}{\text{LTV}} \times 100 \]

Symbol	Meaning	How it is computed
T	total acquisition cost — the first field	everything spent to win customers in the period: media, tools, agency fees, salaries, discounts
N	new customers — the second field	the denominator, and the count that must be greater than zero
LTV	lifetime value per customer — the optional third field	when it is left blank, the three rows that depend on it disappear
CAC	cost to acquire one customer — the main reading	T ÷ N
1000 ÷ CAC	customers acquired per $1,000	the same cost read per $1,000 of spend; hidden when CAC is 0
CAC × 100	cost per 100 customers	the cost scaled to a round cohort
CAC × 1000	spend needed for 1,000 customers	what a much larger push would cost at this rate
LTV ÷ CAC	LTV : CAC ratio	how many times their cost a customer is worth; shown only with an LTV
LTV − CAC	value left per customer after CAC	the value minus the cost of winning it
CAC ÷ LTV × 100	CAC as a share of LTV	the cost as a percentage of the value; six decimals when the division repeats

How to calculate CAC by hand. Divide the cost by the number of customers, and nothing else: 25000 of acquisition cost that produced 500 new customers is a cost of $50 per customer, and the same arithmetic scales down to a single campaign or a single week as long as both numbers cover the same stretch of time and the same definition of a customer. The division is the whole formula — the rest of the card exists because one number cannot say whether $50 is a lot or a little.

The LTV rows collapse when LTV is blank. An empty LTV field is not the same as a zero: blank means “not supplied”, so the LTV : CAC ratio, the value left per customer and the share of LTV are removed from the card entirely rather than printed as dashes or as zeros. A row saying “LTV : CAC 0.00×” would look like a conclusion, when the truth would only be that nobody filled the field in. Entering 0 is a different statement — a customer who brings nothing — and it is accepted as a legal input, with the ratio rows computed from that value; only the share-of-LTV row, which divides by the LTV, has no defined value and collapses.

Precision and boundaries. The acquisition cost and the LTV accept zero or any positive amount, and new customers must be greater than zero because it is the denominator; a negative entry in any of the fields is rejected. Results are rounded to at most six decimals with trailing zeros dropped, so the card prints $50 and 6× rather than $50.000000 or 6.000000×, and a repeating share keeps its useful tail: with a cost of $50 against an LTV of $300 the share of LTV prints 16.666667% rather than 17%. No thousands separators are used anywhere in the output, so a spend of 25000 prints as 25000 and never with a comma, which keeps every string easy to paste into a spreadsheet or a slide. The card is currency-agnostic — dollars, euros or pounds all work as long as the cost and the LTV use the same one — and it does not care what the money bought: miles of transit coverage, square feet of billboard or cm of print space all enter the formula as a single amount, because only the cost, the LTV and the customer count are ever read.

What the Calculator Says When It Cannot Compute

Each rejected input gets its own explanation rather than a silent zero, and the previous result stays on the card so the context of what you had a moment ago is not lost:

• A field left empty, or filled with something that is not a number: Please enter a valid number in the acquisition cost, new customers and LTV fields.
• A negative entry in any field: The acquisition cost, new customers and LTV cannot be negative.
• Zero new customers: New customers must be greater than zero — it is the denominator of CAC, so the cost per customer is undefined at zero.
• Numbers so extreme that the result is no longer a usable finite value: The result is out of range for these inputs.

One row can also disappear without any error. A total acquisition cost of 0 is legal and produces a CAC of $0, and the customers-acquired-per-$1,000 row is then hidden because it divides by the CAC — the same rule that keeps a missing row from meaning two different things: it stands for “cannot be computed from these inputs”, never for “was not worth computing”.

How to Use the CAC Calculator

1. Enter the total acquisition cost in the first field — everything the period’s customer wins cost you: media, tools, agency fees, salaries, discounts. It accepts 0 and any positive amount, and it is the numerator of the ratio.
2. Enter the number of new customers in the second field, counted over the same period as the cost. It is the denominator, so it must be greater than zero; a blank or a zero is refused with an explanation rather than turned into an infinite cost per customer.
3. Read the main reading and the equation. The card is titled “Cost to acquire one customer”, the headline is the cost in dollars, and the equation line replays the arithmetic — with the default numbers it reads $25000 ÷ 500 customers = $50 — so the result can be checked by hand.
4. Work down the breakdown rows: customers acquired per $1,000, cost per 100 customers, and the spend needed for 1,000 customers. Each row carries its own unit, so dollars are never mixed with counts.
5. Add an LTV if you have one. It unlocks the three comparison rows — the LTV : CAC ratio, the value left per customer after CAC, and CAC as a share of LTV — which are what turn the cost into a judgement.
6. Copy or reset. “Copy Result” copies the headline figure as shown, “Copy Summary” copies the summary line together with the equation, and “Reset” returns the fields to the default 25000, 500 and 300.

The card recalculates as you type, so the Calculate button and the Enter key are only shortcuts, and a shared link carries your three inputs so the page can recompute them on arrival. One habit is worth keeping: check the equation line against your own arithmetic before quoting the number, because a mistyped cost shows up there immediately instead of quietly changing every row below it.

Worked Examples You Can Check by Hand

The three examples below are the tool’s own arithmetic, printed the way the card prints it: values without thousands separators, at most six decimals.

Example 1 — $25000 of acquisition cost, 500 new customers and an LTV of $300

This is the card’s default case. The title is Cost to acquire one customer, the main reading is $50, and the equation line shows $25000 ÷ 500 customers = $50. The summary reads CAC $50 — 500 new customers for $25000, LTV : CAC 6×, and the breakdown fills in the rows that make the number readable:

Line in the result card	Value
Customers acquired per $1,000	20
Cost per 100 customers	$5000
Spend needed for 1,000 customers	$50000
LTV : CAC ratio	6×
Value left per customer after CAC	$250
CAC as a share of LTV	16.666667%

Read the rows as three views of one fact. $1,000 buys 20 customers at this rate, so a cohort of 100 costs $5000 and a push for 1,000 customers would take $50000 — the same $50 per customer, scaled. The LTV rows are where the number becomes a decision: $300 of value against a cost of $50 is an LTV : CAC ratio of 6×, which leaves $250 per customer after the cost of winning them, and the cost is a sixth of the value — 16.666667%, printed to six decimals because the division repeats. Against the 3× rule of thumb, 6× is comfortable rather than marginal, but the guideline is not a law: what matters is that the $250 left per customer is real and recurring, not a one-off.

Example 2 — $12000 of acquisition cost, 150 new customers and an LTV of $400

A smaller, more expensive campaign: 12000 spent to win 150 customers, with a customer value of 400. The equation is $12000 ÷ 150 customers = $80, the summary line reads CAC $80 — 150 new customers for $12000, LTV : CAC 5×, and the headline is $80. The rows move with it:

Line in the result card	Value
Customers acquired per $1,000	12.5
Cost per 100 customers	$8000
Spend needed for 1,000 customers	$80000
LTV : CAC ratio	5×
Value left per customer after CAC	$320
CAC as a share of LTV	20%

The comparison with the first example is the useful part. The cost per customer is higher — $80 against $50 — so $1,000 now buys 12.5 customers instead of 20, and a program for 1,000 customers would need $80000 rather than $50000. But the value per customer is higher too: 5× against 6× is a slightly weaker ratio and still well above the 3× guideline, and the $320 left per customer after CAC is larger in absolute terms than the $250 of the first example. A higher CAC is not automatically worse; the ratio and the value left per customer are what decide that. The share of LTV prints as a clean 20% here against 16.666667% before, because 80 ÷ 400 × 100 does not repeat.

Example 3 — $30000 of acquisition cost and 600 new customers, with LTV left blank

The same cost per customer as the first example, on a larger scale, and no LTV entered. The equation is $30000 ÷ 600 customers = $50, the summary reads CAC $50 — 600 new customers for $30000 with no ratio appended, because there is no value to compare against, and the headline is $50. What is left on the card is the cost side only:

Line in the result card	Value
Customers acquired per $1,000	20
Cost per 100 customers	$5000
Spend needed for 1,000 customers	$50000

Three rows are absent rather than blank: the LTV : CAC ratio, the value left per customer and the share of LTV all need a value per customer, so with the field empty they are removed from the card entirely. That is the deliberate convention this family of calculators uses — a row that cannot be computed disappears, so a missing row always means “not computable from these inputs” and never “computed to nothing”. The rows that remain describe a perfectly usable cost: $1,000 buys 20 customers, a cohort of 100 costs $5000, and 1,000 customers would need $50000. If you find the LTV later, typing it in adds the three comparison rows without changing the cost side at all.

What Counts as a Good CAC

The honest answer is that CAC has no universal good value; the useful question is whether the customer is worth more than they cost. The comparison most operators reach for is the CAC LTV ratio — the customer’s lifetime value divided by the cost of winning them — with a common reference guideline of at least 3×, which for a subscription business corresponds roughly to recovering the acquisition cost within twelve months. Read that as a rule of thumb rather than a threshold: 3× is a convention from venture-funded software, not a natural constant, so a business with a long contract and low churn can be content at 2×, while a business selling a one-off, low-margin product may need far more than 3× to survive.

Three habits keep the number honest. First, compare like with like — a blended CAC that divides the whole acquisition budget by all customers is not the same as a channel CAC that divides one campaign’s cost by the customers it produced, and the blended figure is usually the flattering one. Second, check the denominator before celebrating: if a quarter’s new customers include a batch that arrived through a discount, or a definition of “customer” that quietly changed, the CAC falls for a reason that has nothing to do with acquisition getting cheaper. Third, pair the CAC with the LTV calculator and the payback period, because the ratio alone cannot tell you whether the money comes back in one month or in three years.

CAC Calculator FAQ

How do I calculate customer acquisition cost?

Divide the total acquisition cost by the number of new customers it produced — the cac formula is total acquisition cost ÷ new customers. Spending 25000 to win 500 customers is a CAC of $50, and the calculator prints that equation next to the result so the arithmetic can be checked by hand. The numerator should include salaries, tools, agency fees and discounts, not just the media budget.

What is a good LTV : CAC ratio?

A common reference guideline is at least 3×, meaning the customer is worth three times what it cost to win them. It is a rule of thumb rather than a law — 3× roughly equals recovering the acquisition cost within a year for a subscription business — so treat 6× as comfortable, 3× as workable and 1× as a warning that acquisition is not paying for itself. The CAC LTV ratio is best read next to the payback period and the gross margin, not on its own.

What is the difference between CAC and CPA?

CPA counts media spend per conversion, while CAC counts the all-in cost per new customer. The numerator is wider — salaries, tools, agency fees and discounts go into CAC and normally not into CPA — and the denominator is stricter: a new customer rather than a click or a lead. Use the CPA calculator for campaign-level paid media, and CAC for the question of whether the business can afford its own growth.

What happens if I enter zero new customers?

The tool refuses it and explains why: New customers must be greater than zero — it is the denominator of CAC, so the cost per customer is undefined at zero. Zero in the other fields is legal — no spend means a cost of $0 per customer — but a zero denominator has no defined value, so the card keeps the previous result on screen and shows the message instead of an infinite number.

What should be included in total acquisition cost?

Include ad spend, acquisition tools, agency or freelancer fees, the salaries and commissions of the acquisition team and the discounts used to win the customer. Salaries and discounts are the parts most often left out, and leaving them out is what makes a platform-reported CAC and an all-in CAC describe the same month so differently.

Should I leave LTV blank if I do not know it?

Yes — a blank LTV simply removes the three rows that depend on it, so the card shows the cost side without pretending to judge it. Blank and zero are treated differently on purpose: blank means “not supplied” and those rows collapse, while 0 is a legal input meaning the customer brings nothing, and the ratio rows are then computed from that value.

Why does the card show 16.666667% instead of 17%?

Percentages are printed with up to six decimals and trailing zeros dropped, so a repeating share keeps its useful tail instead of being rounded away. A $50 cost against a $300 LTV is 50 ÷ 300 × 100, which the card shows as 16.666667% — exactly the value that would lose meaning if it were rounded to 17%, because 17% would overstate how much of the customer’s value the cost consumes.

Related Tools

CAC, LTV, CPA and ROI answer different halves of the same question. The LTV calculator computes what a customer is worth from revenue, gross margin and churn — the number this page compares the cost against. The CPA calculator measures the narrower, campaign-level cost of a conversion, which is the right check when the question is a specific ad account rather than the business. And the ROI calculator puts any of these figures into the comparison that finally matters: whether the money that went out came back, and by when.