CAC payback calculator with LTV to CAC
Work out how many months it takes to earn back what you spend to win a customer. Enter monthly sales and marketing spend, new customers, revenue per customer, gross margin and churn. Add your work email to see payback, CAC, lifetime value and LTV to CAC, with an AI analysis for your market.
- CAC payback in months
- Customer acquisition cost and monthly gross profit per customer
- Customer lifetime value (gross profit) and LTV to CAC
- A verdict against customer life and the 12-month rule of thumb
- An AI analysis with next steps
This CAC payback calculator divides what it costs to win a customer by the gross profit that customer brings in each month, giving your CAC payback period in months. It also estimates customer lifetime value from your churn rate and compares it with acquisition cost, so you can see how quickly growth pays for itself.
How the calculator works
You enter sales and marketing spend per month (ads, tools, people and agencies used to win new customers), new customers per month, average revenue per customer per month, gross margin and monthly customer churn. Business type and market give the AI analysis context, and currency labels your results.
The example column uses the calculator's default values (illustrative): AED 60,000 of monthly spend, 40 new customers, AED 900 of revenue per customer per month, an 80% gross margin and 2% monthly churn.
| Result | Formula | Example |
|---|---|---|
| Customer acquisition cost (CAC) | Spend ÷ new customers | 60,000 ÷ 40 = AED 1,500 |
| Gross profit per customer per month | Revenue per customer × gross margin | 900 × 80% = AED 720 |
| CAC payback | CAC ÷ monthly gross profit per customer | 1,500 ÷ 720 = 2.1 months |
| Average customer life | 100 ÷ monthly churn % | 100 ÷ 2 = 50 months |
| Customer lifetime value (gross profit) | Monthly gross profit × average life | 720 × 50 = AED 36,000 |
| LTV to CAC | Lifetime value ÷ CAC | 36,000 ÷ 1,500 = 24.0 : 1 |
With 0% churn, lifetime value and LTV to CAC show as n/a. The verdict first checks payback against average customer life, then against a 12-month rule of thumb; longer payback is flagged for tying up more cash. The example's 2.08 months (shown as 2.1) passes both: "You earn back each customer's acquisition cost in 2.1 months, inside the 12-month rule of thumb many SaaS teams use." An analysis with next steps follows, written by AI from your numbers (or rule-based if the AI is unavailable).
How to read your result
Rules of thumb, not laws. A CAC payback of 12 months or less and an LTV to CAC ratio of at least 3:1 are common SaaS rules of thumb. The right line depends on your margin, churn and the cash you have to fund growth.
Treat lifetime value with care. Average life is 100 divided by churn, which assumes churn stays constant: 2% means 50 months, more than four years. The example's 24:1 rests on that assumption, so payback is the safer number to plan cash around. See the CAC payback period and LTV to CAC ratio entries for definitions.
Count every cost of winning customers. If your spend figure leaves out salaries or agency fees, CAC and payback will look shorter than they are.
Notes for GCC and UK teams
Enter revenue per customer without VAT. VAT is collected for the tax authority, not kept, so including it would shorten payback on paper. The standard rate is 5% in the UAE, 15% in Saudi Arabia since July 2020 and 20% in the UK, and Qatar's General Tax Authority lists no VAT among its taxes. The calculator works in AED, SAR, QAR, GBP, USD or EUR, and payback in months is the same in any of them.
When deals take months to close, this month's spend wins later months' customers, so spend and new customers from the same month can distort CAC. Averaging both over a quarter gives a steadier figure.
How Grower helps
Grower's attribution engine de-duplicates conversions across channels and credits each touchpoint with the model you pick, from first click to position-based or your own weights, which shows which channels start the journeys that become customers. In Plan, budgets by month are compared with live spend from connected channels, with budget insights every month.
Frequently asked questions
How do you calculate the CAC payback period?
Divide customer acquisition cost by the gross profit one customer generates each month. With a CAC of AED 1,500 and AED 720 of monthly gross profit (AED 900 of revenue at an 80% margin), payback is 1,500 ÷ 720, or about 2.1 months. CAC itself is sales and marketing spend divided by the new customers it won.
What is a good CAC payback period?
It depends on your margin, churn and cash. Twelve months or less is a common SaaS rule of thumb, not a law, and the calculator's verdict uses it as a reference point. The firmer test is customer life: if payback takes longer than the average customer stays, the average customer never pays back, and the calculator says so.
Why use gross margin instead of revenue?
Because revenue is not what pays back acquisition cost. The costs of delivering your product or service come out first, and only the gross profit left can repay CAC. In the example, AED 900 of monthly revenue at an 80% gross margin leaves AED 720 a month to repay a AED 1,500 CAC, so payback is 2.1 months rather than 1.7.
Want to see which channels bring customers who pay back fastest? Book a demo and we'll connect a channel and show the recommendations it produces. To turn payback into a yearly budget, try the marketing budget calculator.