CAC, LTV & Payback Calculator
Before you scale ad spend, check the math underneath it. Enter your acquisition cost, customers, revenue, margin, and lifespan to see your CAC, LTV, the LTV:CAC ratio, and how many months it takes to earn back what each customer cost.
Inputs
Ad + sales & marketing cost for the period.
Share of revenue left after cost of delivery.
Expected months a customer stays.
Results
Healthy. An LTV:CAC of 3.00× means each customer returns well above what they cost to acquire — typically room to spend more aggressively.
The three numbers that decide if ads scale
Acquisition cost, lifetime value, and the ratio between them.
CAC — customer acquisition cost
Total sales and marketing spend ÷ new customers acquired. It's the all-in price of one customer. Ad cost alone understates it — fold in the sales and marketing effort that turned a click into a paying customer.
LTV — lifetime value
The gross profit a customer generates over their lifetime: monthly revenue × gross margin × lifespan in months. Using margin (not revenue) is what separates a real LTV from a vanity number.
LTV : CAC ratio
How many dollars of lifetime value each acquisition dollar buys. 3:1 is the widely cited healthy target. Below 1:1 you lose money on every customer; far above 3:1 often means you're under-investing in growth.
Why this gates your ad budget
The temptation when a campaign “works” is to pour more money in. But more spend only makes sense if each customer is worth more than they cost to acquire — and stays long enough for that value to actually arrive. A campaign with a great ROAS this month can still sink a business if churn is high and the payback period runs longer than your cash runway.
That's why CAC, LTV, and payback sit upstream of every budget decision. Once the ratio clears 3:1 with a payback you can finance, scaling is a math problem, not a gamble. To check the campaign-level efficiency that feeds CAC, use our CPC, CPM & CTR calculator and ROAS calculator.
How AdFlint connects spend to customers
AdFlint ties conversion tracking to your live ad spend across Google, Meta, and LinkedIn, so your real CAC by channel updates automatically — and budget shifts toward the channels acquiring customers below your target cost.
Questions
What is a good LTV:CAC ratio?
3:1 is the most commonly cited benchmark for a healthy business — three dollars of lifetime gross profit for every dollar spent acquiring a customer. Below roughly 1:1 you're losing money on each customer once overhead is counted. Surprisingly, a very high ratio like 5:1 or more isn't always good news: it often means you're spending too little on marketing and leaving growth on the table, because you could afford to pay more to acquire customers and still be profitable.
Should CAC include more than ad spend?
Yes. A true CAC includes everything spent to acquire customers in a period: ad spend, marketing salaries and tools, sales commissions, and agency or contractor fees, divided by the number of new customers. Using ad spend alone produces a 'blended media CAC' that looks better than reality. For a quick directional read, ad-spend-only is fine; for board-level or fundraising numbers, use fully loaded cost.
Why use gross margin in the LTV formula?
Because revenue isn't profit. If a customer pays you $50/month but it costs $20 to deliver the service, only $30 is actually contributing to covering acquisition cost and overhead. Multiplying lifetime revenue by gross margin converts top-line revenue into the gross profit that genuinely pays back CAC. Skipping margin is the most common way LTV gets overstated.
What is CAC payback period?
It's the number of months it takes a customer's monthly gross profit to repay what you spent acquiring them: CAC ÷ (monthly revenue × gross margin). Most SaaS and subscription businesses aim for a payback under 12 months; under 6 is excellent. Payback matters even more than the LTV:CAC ratio when cash is tight, because a long payback ties up cash even when the lifetime ratio looks healthy.
How do I lower CAC or raise LTV?
Lower CAC by improving targeting and creative so a larger share of clicks convert (a better conversion rate divides the same spend across more customers), by shifting budget toward your most efficient channels, and by improving onboarding so trials become paying customers. Raise LTV by reducing churn (longer lifespan), increasing average revenue per customer through upsells, or improving gross margin. Small gains on both sides compound: a 10% lower CAC and 10% higher LTV improves the ratio by more than 20%.
Free to sign up. Conversion tracking and CAC by platform, automatically.