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CAC Calculator

Customer acquisition cost from sales and marketing spend and new customers, with the LTV:CAC and payback that tell you whether it is too high.

Updated · By Niraj Kumar · 3 sources

Revenue and customers

$

ARPU $100 a month.

Retention

%
0%15%

Customers who cancel each month. 2% a month is 22% a year.

%
−2%5%

Upgrades and added seats less downgrades, from customers who stay. Gives NRR of 92%.

Margin and acquisition

%
0%100%

Revenue left after hosting, support, payment fees and third-party APIs.

$

Ads, tools and the pay of sales and marketing staff. CAC $733.

Cash

$
$

R&D, G&A, rent: everything outside cost of revenue and sales and marketing.

LTV settings

%

What future profit is worth today. 0 for an undiscounted LTV.

months

How long a customer's profit counts. 60 is common.

Customer acquisition cost$733$22,000 of sales and marketing ÷ 30 new customers
Customer lifetime value
$3,091
60 months, discounted 10%; simple LTV $3,900
LTV:CAC
4.2:1
Healthy, at or above 3:1
CAC payback
9.4 months
Under 12 months: efficient
Net revenue retention
92%
Gross retention 78%; 22% of customers lost a year
Implied valuation
$2,457,000
3.4× ARR on 49% growth; Rule of 40: 16
Cash runway
Default alive
Burning $20,200 a month; profitable in month 11, before the cash runs out
What if you pulled one lever?Each row changes one input and leaves the rest as entered. Valuation moves in steps as growth, churn and NRR cross a band.
ChangeLTVLTV:CACPaybackValuationBreak-even
As entered$3,0914.2:19.4 months$2,457,000Month 11
Cut monthly churn by 1 point+$953+1.30–+$1,053,000−2 mo
Add 0.5 points of monthly expansion+$417+0.57––−1 mo
Acquire customers 10% cheaper–+0.47−0.9 mo–−1 mo
Raise gross margin by 5 points+$198+0.27−0.6 mo+$63,000−2 mo
One customer: gross profit less CACCAC not yet earned backProfit after CAC
-$750-$500-$250$0$250$500Payback, month 9.703691215

Expected profit from a new customer, allowing for the chance they churn and for expansion. Simple payback ignores churn: 9.4 months.

Cash in the bank, month by monthShort of cashCash in the bank
$0$250,000$500,000$750,000$1,000,000$1,250,000061218243036

Burning $20,200 a month; profitable in month 11, before the cash runs out. New customers join at today's ARPU; costs stay flat.

Against SMB SaaS benchmarksSmall-business customers, contracts under about $5,000 a year. Checked October 11, 2026.
MetricYoursMedianStrongWhere you sit
Monthly churn2%2%1%Above median
Net revenue retention92%92%102%Above median
Gross margin78%75%82%Above median
CAC payback9.4 months12.0 months8.0 monthsAbove median

How is customer acquisition cost calculated?

CAC is total sales and marketing spend in a period divided by the new customers it won. $22,000 a month for 30 customers is $733 each. On its own CAC says little: compare it with LTV (4.2:1) and payback (9.4 months).

ARPU = MRR ÷ customers; gross profit per customer g = ARPU × gross margin; annual churn = 1 − (1 − c)^12; NRR = ((1 − c) × (1 + e))^12; GRR = (1 − c)^12; simple LTV = g ÷ c; LTV = Σ g × q^t for t = 0 … H − 1, q = (1 − c)(1 + e) ÷ (1 + d)^(1/12); CAC = sales and marketing ÷ new customers; payback = CAC ÷ g; LTV:CAC = LTV ÷ CAC; cash(t+1) = cash(t) + MRR(t) × margin − sales and marketing − other costs; runway = months until cash < 0

This page uses the same method as the SaaS Unit Economics Calculator, which explains each term and assumption in full.

Worked example

An SMB SaaS on $60,000 MRR from 600 customers at $100 a month, adding 30 a month on $22,000 of sales and marketing, with 2% monthly churn, 1.3% monthly expansion, 78% gross margin, $45,000 of other monthly costs and $600,000 in the bank.

  1. 1CAC: $22,000 ÷ 30 new customers = $733
  2. 2Gross profit per customer: $78 a month
  3. 3Payback: $733 ÷ $78 = 9.4 months
  4. 4LTV:CAC: $3,091 ÷ $733 = 4.2:1

CAC $733, earned back in 9.4 months, returning 4.2:1.

Frequently asked questions

What is blended CAC versus paid CAC?

Blended CAC divides all sales and marketing spend by all new customers, including those who came organically. Paid CAC divides paid spend by customers from paid channels only. Blended is the one to report to investors and use for LTV:CAC; paid CAC tells you whether a channel is worth scaling.

Should I lag spend when calculating CAC?

If your sales cycle is long, yes: divide this month's new customers into spend from one or two months earlier, when those deals were sourced. For self-serve products with same-day sign-ups it makes little difference, so this calculator uses spend and customers from the same month.

Sources

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