LTV:CAC ratio: formula, payback and what a good ratio means
How to calculate the LTV:CAC ratio and CAC payback from billing data, why dashboards overstate LTV, where the 3:1 rule comes from, and how churn moves it.
By Florian
The LTV:CAC ratio divides what an average customer is worth over their lifetime (LTV) by what it cost to acquire them (CAC). A ratio of 2.5 means each customer brings back two and a half times their acquisition cost. Compute LTV on gross margin, not revenue, and CAC from all sales and marketing costs, not ad spend alone. There is no official threshold: 3:1 is the target most often quoted, including by Chargebee and Paddle, but neither cites a study for it. A ratio below 1 means you lose money on the average customer even if they stay as long as expected.
The ratio looks simple, and that is the trap. The LTV in your billing dashboard is usually a revenue figure built on a churn rate with its own definition, so the same business can show a healthy or a worrying ratio depending on which numbers go in. This guide gives the formulas, shows how Stripe, Chargebee and Recurly each compute LTV, adds the companion metric (CAC payback), and lists the mistakes that inflate the ratio.
How do you calculate the LTV:CAC ratio?
Three formulas, all monthly:
LTV = average monthly revenue per customer × gross margin ÷ monthly churn rate
CAC = sales and marketing costs in a period ÷ new paying customers in that period
LTV:CAC = LTV ÷ CAC1 ÷ monthly churn is the average customer lifetime in months under a constant churn rate, so LTV is “margin per month × months the customer stays”. This is the form Recurly’s glossary uses, with gross margin in it. For the churn rate itself, see how to calculate churn rate.
A worked example (hypothetical numbers)
A fictional SaaS company spent this in one quarter to win new customers:
| Cost | Amount |
|---|---|
| Ads and sponsorships | $30,000 |
| Sales and marketing salaries, commissions included | $45,000 |
| Tools used by those teams | $5,000 |
| Total | $80,000 |
It won 100 new paying customers in the quarter, so CAC = $80,000 ÷ 100 = $800.
Its customers pay $100 a month on average, its gross margin is 80% and monthly churn is 4%:
LTV = 100 × 0.80 ÷ 0.04 = $2,000
LTV:CAC = 2,000 ÷ 800 = 2.5Each customer returns $2.50 of gross profit for every dollar spent to acquire them, over the lifetime the churn rate implies. You can run your own numbers in the LTV calculator, which also gives CAC payback and the LTV a lower churn would produce.
What goes into CAC?
CAC is every cost of winning new customers, divided by the number of customers won. Recurly’s glossary says it “rolls up every cost that goes into acquiring customers, not just media spend” and lists ads, sales and marketing salaries and commissions, agency fees, software and overhead. Paddle’s definition is similar: anything on your P&L that contributes to acquiring new customers.
Decisions to make once and keep:
- Blended or paid CAC. Blended CAC divides all acquisition costs by all new customers, including those who came through word of mouth or search. Paid CAC keeps only the customers and costs of paid channels. Blended CAC flatters the paid channels; report both if you buy traffic.
- Paying customers only. If you have a free plan or trials, count customers when they first pay. Free users are not in billing metrics: Stripe’s active subscribers only include subscribers with positive MRR.
- The time lag. Spend in March may convert in May. For long sales cycles, compare a period’s costs with the customers won one cycle later, or use a trailing quarter on both sides.
- Salaries and tools. Leaving out the people who sell and market is the most common way to cut CAC on paper. Include them, prorated if they also work on retention.
- New customers, not reactivations. A customer who returns after cancelling did not cost a new acquisition. Count them apart, as for retention metrics.
Which LTV does your billing tool show?
Most billing dashboards show an LTV, and none of the three below is the margin-based figure the ratio needs. Each also defines churn its own way.
| Tool | LTV formula | Gross margin? | Churn as defined there |
|---|---|---|---|
| Stripe Billing analytics | ARPU ÷ subscriber churn rate | No | Subscribers churned in the past 30 days ÷ (active subscribers 30 days ago + new subscribers in the past 30 days) |
| Chargebee RevenueStory | Revenue per paid subscription × subscription lifetime | No | Lifetime is the inverse of the average of the last three months’ churn rates |
| Recurly, LTV by plan | ARPS × (1 + d) ÷ (d + churn), with a discount rate d of 1% a month by default | No | Churned subscriptions ÷ subscriptions active at any point in the month |
| Recurly glossary | Revenue per customer × gross margin ÷ churn | Yes | Customer churn rate |
Three consequences:
- Dashboard LTV is revenue LTV. To use it in the ratio, multiply by your gross margin. At 80% margin, a dashboard LTV of $2,500 is $2,000 of gross profit.
- Churn definitions with new customers in the denominator give a lower churn rate, so a higher LTV. Stripe and Recurly both include customers who joined during the period.
- Recurly discounts future revenue. A dollar in month 30 is worth less than a dollar today. Its formula with a 1% monthly rate gives a lower LTV than the plain one.
The chart applies these choices to the example above:
Example data, not a benchmark
Same customers, same costs: 3.13 with revenue LTV ($2,500), 2.50 with gross-margin LTV ($2,000), 2.02 with gross margin and Recurly’s discount formula ($1,616). Whichever you choose, write the definition next to the number and keep it from month to month.
What is a good LTV:CAC ratio?
No standard or accounting rule defines one. What exists:
- The 3:1 rule of thumb. Chargebee’s glossary says the ratio “should be 3:1”, and Paddle’s says the ideal ratio “is widely accepted to be 3:1”. Neither page cites the study or data behind it. Chargebee also shows targets by industry, again with no source; we do not repeat them.
- The arithmetic. Below 1, the average customer’s lifetime gross profit does not cover their acquisition cost: growth loses money. At exactly 1 you only break even, and only if customers stay as long as the churn rate implies.
- Your own trend. Recurly recommends benchmarking CAC payback against “a company’s own historical trend”. The same logic holds for the ratio, because its inputs depend so much on definitions that comparing with another company’s figure rarely means much.
A ratio far above your usual level is not automatically good news either. It can mean churn fell, or it can mean you spent little on acquisition that period and could grow faster.
What is CAC payback and why look at it too?
The ratio says whether customers are worth acquiring over their lifetime. It does not say when you get your money back, and cash runs out before lifetimes end. CAC payback answers that:
CAC payback (months) = CAC ÷ (monthly revenue per customer × gross margin)This is Recurly’s formula. In the example, 800 ÷ (100 × 0.80) = 10 months. Chargebee’s glossary divides CAC by monthly revenue without the margin, which gives 8 months for the same business. Use the margin version, for the same reason as for LTV.
Payback also shows what the ratio hides. With 4% monthly churn, 0.96 to the power of 10 = 66% of a cohort is still there after 10 months: about a third of the customers leave before they have paid back their acquisition cost.
Which mistakes inflate the ratio?
1. Revenue instead of margin
The most common one, and dashboards make it the default. Recurly’s glossary warns that using revenue in place of margin “overstates lifetime value”.
2. A constant churn rate on young customers
1 ÷ churn assumes every month looks the same. Recurly notes that churn “is usually highest early in the relationship”, so the shortcut “can overstate lifetime value for young cohorts”. If most of your customers are recent, check LTV against what real cohorts have paid so far.
3. Very low churn, absurd lifetimes
At 0.5% monthly churn, 1 ÷ churn is 200 months, almost 17 years. Few businesses can plan on that. Cap the lifetime at a horizon you can defend, such as three or five years, and say so.
4. Past-due customers counted as active
Stripe’s MRR includes active and past_due subscriptions, and a subscriber only counts as churned once all their subscriptions are canceled or unpaid. While dunning runs, failed payments are not churn yet, which lowers the churn rate and raises LTV. If retries last weeks, the dashboard LTV is ahead of what you collect.
5. Customers and subscriptions mixed up
Stripe’s LTV counts subscribers; Chargebee’s counts paid subscriptions. A customer with two subscriptions is one customer in CAC but can be two in LTV. Use the same unit on both sides.
6. Different periods on each side
LTV from this month’s churn, CAC from last year’s spend. Use the same period, or trailing averages of the same length, for both.
How do you improve the LTV:CAC ratio?
The ratio has four levers: revenue per customer, gross margin, churn and CAC. Churn has the most leverage because it sits in a denominator. In the example, cutting monthly churn from 4% to 3% raises LTV from $2,000 to $2,667, a third more, and the ratio from 2.50 to 3.33, without spending a dollar more on acquisition.
Part of that churn involves no decision to leave: subscriptions end because a renewal payment failed and was never recovered. That share is often the fastest to reduce, with retries timed to the decline reason, a card update link and a few clear emails. See involuntary churn. For voluntary churn, cancel flows that answer the reason given (a pause, a cheaper plan) and win-back emails after cancellation both lengthen the average lifetime. The definition of LTV used across this guide is in the glossary: customer lifetime value.
Lowering CAC usually takes longer: better conversion of trials, channels with less paid spend, a shorter sales cycle. Raising prices lifts revenue per customer, but it can raise churn too; measure both.
FAQ
What does an LTV:CAC ratio of 3 mean?
It means the average customer is expected to bring in three times their acquisition cost over their lifetime. If LTV is computed on gross margin, that is three dollars of gross profit for each dollar of sales and marketing spent to win them. If it is computed on revenue, the real figure is lower.
Is LTV:CAC calculated with revenue or gross margin?
Gross margin, because acquisition costs are paid out of profit, not revenue. Recurly’s glossary uses margin and warns that revenue overstates LTV. Billing dashboards (Stripe, Chargebee RevenueStory, Recurly’s LTV by plan) show revenue-based LTV, so multiply it by your gross margin before using it in the ratio.
Can the LTV:CAC ratio be too high?
It can be a sign you are underinvesting in growth: if each customer pays back their acquisition cost many times over, spending more to acquire customers could still be profitable. Check CAC payback and cash before deciding; a high ratio with a long payback still ties up cash.
How often should you calculate LTV:CAC?
Monthly or quarterly, with the same definitions each time. Use trailing averages (for example the last three months of churn and spend) to smooth out one-off months, and recompute after a price change or a large change in acquisition spend.
How NoChurn helps
NoChurn works on the churn side of the ratio. It recovers failed payments with retries and recovery emails, runs cancel flows with an offer per reason and one-click cancel always visible, sends win-back emails at day 30, 60 and 90, and scores each customer’s churn risk. It connects to Stripe in one click and works with Chargebee, Recurly, Paddle, Braintree and others, or with any billing through the API. Pricing depends only on MRR, free up to $300 of MRR and with no commission on recovered revenue (your own domain for emails and hosted pages is a $14.99/month add-on on any plan).
Sources
All accessed 14 November 2026.
- Analytics (MRR, subscriber churn rate, subscriber lifetime value), Stripe documentation
- How is the lifetime value metric calculated in RevenueStory?, Chargebee documentation
- LTV by plan, Recurly documentation (updated 19 August 2026)
- Customer lifetime value (LTV / CLV), Recurly glossary
- Customer acquisition cost (CAC), Recurly glossary
- CAC payback period, Recurly glossary
- LTV CAC ratio, Chargebee glossary
- CAC payback period, Chargebee glossary
- Customer acquisition cost (CAC), Paddle