Find out whether growth is making you money
Enter what you spend and what a customer is worth. You get blended and paid CAC, margin-based LTV, the LTV:CAC ratio, your payback period, and the churn sensitivity that usually decides the answer.
Paid search takes roughly four times longer to pay back than referral, and longer than your median customer has stayed. Every customer it wins is funded well before it is earned.
Why this tool exists
Most companies can tell you what they spent on marketing last month and roughly how many customers they won. Very few can tell you what a customer is actually worth after cost of delivery, how long the average one stays, or how many months it takes to earn back what acquiring them cost. Those three numbers decide whether growth builds the business or quietly drains it.
The common shortcut of ad spend divided by new customers undercounts CAC by leaving out salaries, agency retainers, tooling and sales commission, often by a factor of two or more. On the other side, revenue-based LTV flatters every business that has a cost of delivery. Put an understated CAC next to an overstated LTV and you get a ratio that looks healthy while the bank balance says otherwise.
This calculator loads both sides of the equation properly: every acquisition cost on one side, gross-margin lifetime value on the other, with expansion revenue netted against churn. It then runs a churn sensitivity table, because in most subscription businesses retention moves LTV further than anything the acquisition team can do.
- Blended, paid and organic CAC calculated separately, and the paid number is the one that guides media decisions
- Margin-based LTV, plus a discounted NPV view for cash-flow planning
- LTV:CAC and payback period scored against the bands investors actually apply
- The maximum CAC you can afford and still hold a 3:1 ratio
- A churn sensitivity table showing what better retention is worth in cash
Who it's for
Anyone who has to defend a growth budget with numbers rather than conviction.
Need to know whether scaling spend compounds value or compounds a loss.
Need a defensible CAC to justify the next increment of budget.
Need payback period and NPV, not just a ratio on a slide.
Live and die on net churn, and this quantifies exactly how much.
Model repeat purchase frequency into a real lifetime value.
Need a ceiling on CAC before setting channel bid strategy.
Sanity-check the unit economics behind a growth plan in minutes.
Show a client the CAC headroom that justifies a larger programme.
How it works
Four inputs, live output. Nothing to install and nothing to submit.
Media, team, tools and sales cost: everything that buys a customer
Revenue per customer, gross margin, churn and expansion
Ratio, payback and churn scored against standard bands
Move churn or margin and watch LTV respond in real time
Media, team, tools and sales cost: everything that buys a customer
Revenue per customer, gross margin, churn and expansion
Ratio, payback and churn scored against standard bands
Move churn or margin and watch LTV respond in real time
Features
Built to answer the follow-up questions, not just the first one.
Blended, paid and organic CAC
Splits acquisition cost by source so you can see the true cost of the next paid customer, which the blended number hides.
Gross-margin LTV
Lifetime value calculated on gross profit, with an optional discounted NPV view for finance.
Health scoring
Your ratio, payback period and churn rate scored against the thresholds investors and boards apply.
Cohort payback curve
Cumulative gross profit per customer, month by month, starting at minus CAC. Where it crosses zero is your payback month.
Churn sensitivity table
Five churn scenarios side by side, so you can price what a retention improvement is actually worth.
Shareable scenarios
Every input is encoded in the URL. Send a link and the recipient sees your exact scenario.
What you'll get
Everything on one screen, updating as you type.
Blended, paid and organic, fully loaded with team, tools and sales cost.
Margin-based, with a discounted view and average customer lifetime.
Scored, colour-coded, and explained in plain language.
The most you can pay for a customer while holding a healthy ratio, which is the number that should set your bid caps.
What LTV becomes if churn halves, or doubles.
Every input and output, ready to paste into a board deck or model.
See it in action
PreviewA preview of what the calculator returns. Run it on your own numbers to see yours, with no account to create.
Paid search takes roughly four times longer to pay back than referral, and longer than your median customer has stayed. Every customer it wins is funded well before it is earned.
Why it's worth five minutes
A ratio below 1:1 means every new customer costs more than they return. Better to learn that from a calculator than from a cash-flow statement.
The max affordable CAC is a hard number you can hand to whoever manages your bids.
Once churn's effect on LTV is on screen, the case for retention work stops being a matter of opinion.
Payback period and NPV are the two figures a CFO asks for. Both are here.
Use cases
Where this calculator settles an argument.
Spending on ads with no idea whether the economics support it.
Load in media, founder time and tooling; set churn from the last six months.
A real CAC, usually two to three times the number they had been quoting, and a clear view of whether to scale or fix retention first.
Profitable on first order, unsure whether repeat purchases justify higher bids.
Switch to the transactional model and enter purchase frequency and margin.
A lifetime value that supports a higher acquisition ceiling, and the confidence to outbid competitors who only price the first order.
Client sees the retainer as a cost rather than an investment.
Model the client's current economics, then the same model with improved conversion.
A shared scenario link showing the retainer's payback in the client's own numbers.
Investors asking for unit economics the team has never formally calculated.
Fill in the inputs, export the CSV, and paste the outputs into the deck.
Consistent, defensible metrics with the assumptions written down next to them.
The thinking behind it
This calculator does not guess. Every figure it shows follows from an input you supplied, using formulas that are standard in the field, which means you can audit any number on the page rather than trusting a black box.
The judgement is in the conventions, and they are chosen deliberately. LTV is gross-margin based because revenue LTV overstates the value of every business with a cost of delivery. Lifetime is one divided by net churn, with expansion revenue subtracted from churn first. Net churn is floored at 0.5% per month so a negative-churn business returns a large but finite number instead of infinity.
The verdicts apply the thresholds used across the industry: 3:1 as the LTV:CAC floor, 12 months as a healthy payback ceiling, and above 5:1 read as underinvestment rather than success, because a very high ratio usually means demand generation, not economics, is the constraint.
Media, salaries, retainers, tooling and sales commission all count. Excluding them is the most common reason a CAC figure is wrong.
Every lifetime value here is calculated on gross profit, so cost of delivery is visible rather than hidden.
A single point estimate invites false confidence. The churn table shows you the range your business actually lives in.
Frequently asked questions
Related resources
Go deeper on the numbers behind the calculator.
Know your numbers before you scale them
Growth multiplies whatever your unit economics already are. Five minutes with the calculator tells you which direction that multiplication runs.