Free Calculator

    Customer Acquisition Cost Calculator

    Calculate your CAC, customer LTV, LTV:CAC ratio, and CAC payback period in real time. Built for B2B service businesses evaluating growth investment.

    Your Inputs

    Your Results

    Total CAC Spend / mo$15,000
    Customer Acquisition Cost$600
    Customer Lifetime Value$39,600
    LTV : CAC Ratio66.00 : 1
    CAC Payback Period0.3 mo

    Healthy B2B service businesses run LTV:CAC ratios of 3:1 or higher and CAC payback under 18 months. Below those thresholds, unit economics are tight.

    How to Read These Numbers

    • LTV:CAC of 3:1 or higher means your unit economics work. Reinvest in growth.
    • LTV:CAC between 2:1 and 3:1 means margins are tight. Focus on either lifting LTV (retention, upsell) or cutting CAC (conversion optimization, better targeting).
    • LTV:CAC below 2:1 means you are paying close to what each customer is worth. Stop scaling spend until you fix the economics.
    • CAC payback under 12 months is excellent. Cash flow recovers fast and you can compound growth.
    • CAC payback above 24 months creates cash flow strain unless you have outside funding.

    Why acquisition cost is the number that decides how fast you can grow

    Every service business has a ceiling on growth, and it is almost never ambition. It is the relationship between what one new customer costs to win and what that customer is worth once the work is delivered and paid for. Get that relationship right and marketing becomes a machine you can feed. Get it wrong and every extra dollar of spend accelerates a loss.

    The trouble is that most owners carry a rough figure in their head that only counts advertising. Real acquisition cost includes the salesperson's time on unqualified calls, the proposal that took four hours and went nowhere, the software subscriptions, and the share of an owner's week spent on business development. Once those are in, the number is usually somewhere between two and four times the remembered one.

    This tool asks for both sides of the equation because neither means anything alone. A three thousand dollar acquisition cost is reckless for a business whose customers spend two thousand dollars once, and conservative for one whose customers stay four years on a monthly agreement.

    One more habit worth building: run the calculation twice, once with the figures you believe and once with the figures your bank statements and invoices support. The gap between those two runs is usually where the real decision sits, because it shows how much of your current confidence rests on estimation rather than evidence. Owners who close that gap tend to make faster budget decisions afterwards, since they no longer have to argue about the inputs every time the subject of increasing spend comes up.

    What each field is doing to the result

    Two of these inputs move the output far more than the others, and knowing which changes where you spend your attention.

    Sales cost belongs in the calculation, not beside it

    Commission, salary time spent on prospects who never buy, travel to site visits and the hours spent writing quotes are all part of winning the customer. Businesses that count only advertising typically understate acquisition cost by forty percent or more, which makes an unprofitable channel look fine for a year.

    Gross margin is what converts revenue into something you can spend

    A customer paying four thousand dollars at fifty five percent margin contributes twenty two hundred. Only that contribution can repay acquisition cost. Running the maths on revenue rather than margin is the single most common reason a business with growing sales runs out of cash.

    Retention length is the quietest lever with the loudest effect

    Extending average retention from twelve months to eighteen raises lifetime value by half without winning a single extra customer. In practice that is usually cheaper to achieve than reducing acquisition cost by the same proportion, and it also improves referral volume.

    Payback period governs how fast you are allowed to grow

    Lifetime value can look healthy while payback takes two years, and that combination will strangle a business without external funding. Payback tells you how much cash sits tied up in each new customer before they become self-funding, which sets the pace at which you can safely increase spend.

    What to do with the numbers you get

    1. 1If the value to cost ratio is below three, do not scale. Fix qualification first, because most of the excess cost is coming from time spent on prospects who were never going to buy.
    2. 2If the ratio is above five, you are almost certainly underinvesting. Competitors with worse economics are buying attention you could afford, and that compounds against you over a couple of years.
    3. 3If payback runs past eighteen months, look at pricing and at whether any part of the fee can be collected up front. Deposits and onboarding fees shorten payback immediately without changing a single campaign.
    4. 4Recalculate by service line rather than for the business as a whole. Blended figures hide the one offering that is subsidising everything else, and that offering is usually easy to identify once separated.
    5. 5Track the number quarterly. Acquisition cost drifts upward quietly as competitors enter a market, and the businesses that notice late are the ones that only look once a year.

    Where the number misleads people

    • Referral customers usually cost far less to acquire and distort the blended average. Separate them out or you will credit paid channels with efficiency they did not earn.
    • Retention estimates taken from memory are almost always optimistic. Pull them from invoices rather than impressions.
    • Very small customer counts produce unstable results. Fewer than around ten new customers in the period means the figure is directionally useful at best.
    • Seasonal businesses should run this across a full year. A single quarter measured in peak season produces a number that will not survive January.

    Common questions

    Should the owner's own time count as a sales cost?

    Yes, valued at what you would pay someone to do it. Owner-led selling makes acquisition cost look artificially low, right up until the owner runs out of hours and growth stops for reasons nobody can explain from the reports.

    What ratio should a service business aim for?

    Three to one is the usual floor for sustainability. Between three and five is a healthy operating range. Above five suggests you are leaving growth on the table rather than running an unusually efficient business.

    How does this differ from cost per lead?

    Cost per lead measures the top of the funnel and can be improved by generating cheaper and worse leads. Acquisition cost measures the bottom and cannot be gamed the same way, which is why it is the number worth reporting to an owner.

    Does acquisition cost naturally rise as you grow?

    Usually, yes. The cheapest demand gets captured first, and expansion reaches audiences with less existing intent. Plan for a gradual rise rather than assuming today's efficiency holds at three times the volume.