Start free →
Free calculator

SaaS Unit Economics Calculator

Is each customer actually profitable? Enter your revenue per account, gross margin, churn and CAC to get LTV, the LTV:CAC ratio and how many months until a customer pays back their acquisition cost.

Per customer

$
%
%
$
LTV : CAC ratio
4.4×
Customer LTV
-
CAC payback
-
Gross profit / mo
-
Avg lifetime
-

What good unit economics look like

LTV = monthly gross profit per customer ÷ churn (ARPA × gross margin ÷ churn). The two rules of thumb investors use: an LTV:CAC of 3× or higher, and a CAC payback under ~12 months. Below 3× you're spending too much to acquire relative to what a customer is worth; a long payback ties up cash and lengthens your runway. The curve shows cumulative gross profit from one customer, it starts at minus your CAC and crosses zero at the payback month.

Worked example: a $100-a-month SaaS customer

A customer paying $100 a month at 80% gross margin and 3% monthly churn, acquired for $600, clears both rules of thumb.

Default inputs of the calculator above. Change any input to run your own numbers.
ItemValue
ARPA (revenue per account per month)$100
Gross margin80%
Monthly churn3%
CAC$600
Gross profit per month ($100 × 80%)$80
Average lifetime (1 ÷ 3%)33 months
Customer LTV ($80 ÷ 3%)$2,667
CAC payback ($600 ÷ $80)7.5 months
LTV:CAC ratio ($2,667 ÷ $600)4.4×

Embed this calculator on your site

Free to use. Copy the snippet, it drops the calculator into any page and adds a small credit link back here.

Frequently asked questions

How do you calculate unit economics for a SaaS company?
Work out what one customer earns and costs. Gross profit per month = ARPA × gross margin, lifetime = 1 ÷ monthly churn, LTV = gross profit × lifetime, then compare LTV with CAC and divide CAC by monthly gross profit for the payback period. The full method is in the SaaS unit economics guide.
What is the LTV formula?
LTV = ARPA × gross margin ÷ monthly churn. With the defaults, $100 × 80% ÷ 3% = $2,667. Using gross profit instead of revenue matters: revenue-based LTV overstates what a customer is worth.
What is a good LTV:CAC ratio?
The rule of thumb investors use is 3× or higher. Below 3× you spend too much to acquire a customer relative to what they are worth. See the LTV:CAC ratio guide.
How do you calculate CAC payback?
CAC payback = CAC ÷ (ARPA × gross margin). $600 ÷ $80 = 7.5 months with the defaults. The usual rule of thumb is under about 12 months. More in CAC payback period.
Why does churn move LTV so much?
Lifetime is 1 ÷ churn, so halving churn doubles LTV. At 1.5% monthly churn instead of 3%, the default customer is worth $5,333 and LTV:CAC rises from 4.4× to 8.9×.
Should I look at LTV:CAC or CAC payback?
Both. LTV:CAC tells you whether a customer is profitable over their life; payback tells you how long your cash is tied up before they are. A high ratio with a long payback can still drain runway. The CAC payback calculator goes deeper on the second.

Email yourself these numbers

Get the result in your inbox plus occasional SaaS-finance playbooks. No spam.

Cite this page

Citation

Adlega. "SaaS Unit Economics Calculator: LTV, CAC, Payback." Updated October 22, 2026. https://adlega.com/blog/tools/unit-economics/

Link for your article

<a href="https://adlega.com/blog/tools/unit-economics/">SaaS Unit Economics Calculator: LTV, CAC, Payback</a> (Adlega, updated October 22, 2026)

Plan the whole picture in Adlega

Adlega turns these one-off numbers into a live financial model for your SaaS, projections, scenarios, dashboards.

Try Adlega free