Quick answer
Customer acquisition cost (CAC) is what you spend on marketing and sales to win one new customer. Lifetime value (LTV) is the gross profit that customer brings over the whole relationship. Marketing pays for itself when LTV comfortably exceeds CAC — and when the first purchases arrive soon enough to cover the spend. Borrowing for marketing makes most sense when both numbers are known, not guessed.
Key points
- CAC = marketing and sales spend ÷ new customers won.
- Lifetime value should use gross profit, not revenue.
- The LTV-to-CAC ratio shows whether marketing is worth scaling; the CAC payback shows how fast.
- Acquisition cost usually rises as you spend more — plan for it.
- CAC
- Spend ÷ new customers
- Lifetime value
- Gross profit per purchase × purchases per customer
- CAC payback
- CAC ÷ monthly gross profit per customer
Marketing is the most measurable growth move a business can make — and one of the least measured. Many owners know what they spend on ads but not what each new customer costs, or what that customer is worth over time. Those two numbers decide whether borrowing to market is a smart boost or an expensive experiment.
What is customer acquisition cost?
Customer acquisition cost (CAC) is the total cost of winning one new customer:
CAC = marketing and sales spend in a period ÷ new customers won in that period
Include everything aimed at winning new business: ad spend, agency or freelancer fees, promotional offers, trade shows, sponsorships, and the portion of any salesperson’s time spent chasing new customers. Exclude spend aimed at existing customers, such as loyalty emails, or you’ll overstate CAC.
What is customer lifetime value?
Lifetime value (LTV) is the gross profit a customer brings over the whole relationship:
LTV = gross profit per purchase × average number of purchases per customer
Or, for recurring services:
LTV = monthly gross profit per customer × average months a customer stays
Use gross profit, not revenue. A customer who spends $1,000 with you at a 30% margin is worth $300 towards covering acquisition cost — not $1,000. The gross margin guide explains how to find the right margin.
How do CAC and LTV decide whether marketing pays back?
Two measures matter:
| Measure | Formula | What it tells you |
|---|---|---|
| LTV ÷ CAC | Lifetime gross profit per customer ÷ acquisition cost | Whether marketing is worth scaling at all |
| CAC payback | Acquisition cost ÷ gross profit per customer per month | How quickly each customer repays what they cost to win |
A high ratio with a slow payback means marketing is valuable but ties up cash for a while — exactly where a funding facility can help. A fast payback with a thin ratio means cash comes back quickly but there’s little left over. You want both to look healthy, especially if the marketing is funded with borrowed money.
A worked example (illustrative)
A mobile dog-grooming business spends $4,500 a month on social ads and local search and wins about 50 new clients, so CAC is $90. The average client books a groom every six weeks — roughly nine times a year — at $95 a visit. After products, fuel and the groomer’s pay, gross profit is about $40 a visit.
Records show the average client stays about two years, so lifetime value is roughly 18 visits × $40 = $720. The LTV-to-CAC ratio is 8 — a strong result. CAC payback is quick: nine visits a year is about $30 of gross profit a month per client, so each client repays their acquisition cost in about three months.
The owner wants to add a second van and double ad spend to $9,000 a month. Expecting CAC to rise to around $120 at the higher spend, the ratio is still 6 and payback about four months. Funding the extra spend alongside the van — while the second groomer builds a full book — is a sensible growth move. Before borrowing, the owner runs the whole plan through the Growth ROI calculator, treating the groomer’s wage and van costs as new running costs. When the plan checks out, the next step is simple: see what the expansion could qualify for.
Why does CAC rise when you scale?
- The easy customers go first. Early spend reaches people already looking for you.
- Bids go up. Competing harder for the same audiences raises ad costs.
- Audiences tire. People who’ve seen your ad many times stop responding.
- New channels are less proven. Expanding into unfamiliar platforms usually starts at a higher CAC.
Scale in steps. Increase spend, measure CAC for a few weeks, then decide on the next step. Our guide on how much to spend on marketing covers budgeting in stages.
How do you track CAC without an analytics team?
- Ask every new customer how they found you, and record it.
- Use separate phone numbers, discount codes or landing pages for each channel.
- Tag website links so sales can be traced to the ad that brought them.
- Review monthly: spend by channel, new customers by channel, CAC by channel.
Even rough tracking beats none. A CAC estimate that’s 20% out still tells you whether a channel is wildly profitable or quietly losing money.
How does this fit a marketing loan?
Lenders don’t usually ask for CAC and LTV, but knowing them helps you ask for the right amount and the right structure. A business with fast CAC payback might suit a line of credit for growth, drawn and repaid in step with each campaign. A business with a strong ratio but slower payback — such as a subscription service — may prefer a fixed loan over a longer term. See borrowing for marketing for more.
Know what a customer is worth? Let’s fund winning more of them
If each new customer is worth several times what they cost to win, marketing is one of the best growth moves you can make. Tell us what you’d spend, what it’s delivered so far and what you’re aiming for.
Tell us about the channels, the spend and the customers they bring. The form is short, no credit check happens when you first send it, and your enquiry isn’t sprayed across a list of lenders. Someone who understands marketing maths will call you back. Accurate figures on turnover and spend help us suggest a facility that suits your campaign cycle.
Frequently asked questions
How do I calculate customer acquisition cost?
Add up what you spent on marketing and sales in a period — ad spend, agency fees, promotional costs and the share of sales wages spent winning new customers — and divide by the number of new customers won in that period.
How do I calculate customer lifetime value for a small business?
Multiply the gross profit from an average purchase by the average number of purchases a customer makes before they stop buying. For subscription or contract businesses, multiply monthly gross profit per customer by the average number of months customers stay.
What is a good LTV to CAC ratio?
There's no universal number, but the gap needs to be wide enough to cover overheads, the cost of finance if you borrowed for marketing, and the risk that customers don't stay as long as expected. A ratio close to one means marketing barely pays for itself.
Why does acquisition cost rise when I spend more?
Your first marketing dollars reach the most responsive customers. As spend increases you reach people who are less ready to buy, bids for ads rise and audiences tire of seeing you. Expect CAC at double the spend to be higher than today's, and test before committing.