Free tool
Use this CAC calculator to understand how much it costs to acquire a customer from your marketing or paid media spend. Calculate customer acquisition cost, cost per lead, lead-to-customer conversion rate and an optional LTV:CAC ratio.
CAC
£400
Cost per lead
£40
Lead → customer
10%
LTV : CAC
6 : 1
At or above the 3:1 benchmark
Spend → leads → customers
Efficient — LTV:CAC of 6:1
Customer acquisition cost, or CAC, measures how much a business spends to acquire a new customer. In paid media planning, CAC is useful because it connects advertising spend to commercial outcomes rather than only reporting leads, clicks or traffic. A CAC calculator helps marketers understand whether acquisition activity is efficient and whether future budget increases are likely to remain commercially viable.
The headline number is simple, but its value comes from the funnel underneath it. Spend buys leads, leads convert to customers, and customers carry a lifetime value. Reading those three relationships together turns CAC from a vanity metric into a planning input you can actually act on.
Basic CAC divides total marketing and sales spend by the number of customers acquired in the same period: CAC = total spend ÷ customers acquired. Alongside it, this calculator works out cost per lead (spend ÷ leads) and the lead-to-customer conversion rate (customers ÷ leads). If you add a lifetime value it returns the LTV:CAC ratio, and if you add MRR and gross margin it estimates the payback period — how many months of gross profit it takes to earn the acquisition cost back.
CAC is usually the metric that decides whether growth is sustainable. A campaign can generate impressive lead volume while quietly acquiring customers above what they are worth. Because paid media is the largest controllable input into CAC, it is also the lever most worth forecasting: as spend rises, channels move along their saturation curve and the marginal cost of each additional customer climbs. Planning on the blended CAC you posted last month therefore understates what the next tranche of budget will actually cost.
Cost per lead measures the cost of generating an enquiry; CAC measures the cost of turning enquiries into paying customers. The gap between them is conversion. Two channels can share an identical CPL yet produce wildly different CACs once close rates differ, which is why optimising to CPL alone can quietly degrade acquisition economics. Looking at both — and the conversion rate that links them — keeps the focus on customers, not just leads.
In lead generation, CAC sits at the end of a longer chain: spend buys leads, sales qualifies and closes them, and only then is a customer acquired. Small movements in lead quality or close rate swing CAC far more than CPL suggests. Forecasting that chain is the job of the paid media forecast calculator, which turns budget and conversion assumptions into expected leads and cost per lead before spend is committed.
For subscription businesses, CAC is only half the story — the other half is how quickly it is repaid. The two metrics that matter are the LTV:CAC ratio, where 3:1 or better is a common health benchmark, and the payback period, the number of months of gross profit needed to recover the acquisition cost. A business can run a high CAC profitably if retention is strong and payback is short; a low CAC can still be dangerous if customers churn before they pay back.
There are only three real levers: acquire more efficiently, convert better, or grow customer value. Reallocating budget toward the channels with the strongest marginal return — the focus of the budget reallocation calculator and the marginal ROAS calculator — lowers CAC without touching the funnel. Lifting conversion rate or order value lowers it from the other direction. The mistake to avoid is scaling spend on a saturated channel, which raises CAC for every acquisition, not just the incremental ones.
This calculator measures where acquisition stands today. ElenIQ’s Dex takes the next step: forecasting how a change in budget is likely to move CPL, CAC and pipeline before a penny is spent. Because the forecast accounts for each channel’s saturation and marginal return, you can see whether a planned increase keeps acquisition commercially viable — rather than discovering a higher CAC after the spend has already gone out.
CAC, or customer acquisition cost, is the total amount a business spends to acquire one new customer. It is calculated by dividing total marketing and sales spend by the number of customers acquired in the same period. CAC connects advertising spend to commercial outcomes rather than only reporting leads, clicks or traffic.
CAC = total marketing spend ÷ customers acquired. If you spend £20,000 and acquire 50 customers, your CAC is £400. To understand the funnel behind it, also calculate cost per lead (spend ÷ leads) and the lead-to-customer conversion rate (customers ÷ leads).
There is no universal “good” CAC because it depends on what a customer is worth. The clearest test is the LTV:CAC ratio: a healthy SaaS or subscription business usually targets at least 3:1, meaning a customer is worth at least three times what it cost to acquire them. A ratio below 1:1 means you lose money on every acquisition.
CPL (cost per lead) measures the cost of generating an enquiry; CAC (customer acquisition cost) measures the cost of converting those enquiries into paying customers. CPL ignores lead quality and close rate, so two channels with identical CPLs can have very different CACs once conversion is taken into account.
Paid media is usually the largest controllable input into CAC. As you scale spend, channels move along their saturation curve and the marginal cost of each additional customer rises, so CAC tends to climb with budget. That is why forecasting CAC before increasing spend matters more than reading last month’s blended figure.
Yes. Because CAC is driven by spend, conversion rates and channel saturation, it can be modelled forward. ElenIQ’s Dex forecasts how budget changes are likely to move CPL, CAC and pipeline before spend is committed, so you can see whether a planned increase stays commercially viable.
Use Dex to forecast how budget changes could impact CAC, CPL and pipeline before spend is committed — so acquisition stays viable as you scale.
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