The LTV:CAC ratio compares the lifetime gross profit from a customer, or LTV, to the cost of acquiring that customer, or CAC. A ratio of 3:1 means you earn $3 in gross profit for every $1 spent on acquisition. It is the single most important unit economics metric for subscription businesses, used by investors to evaluate whether a business model is viable and scalable.
By Pitchkit · Last Updated October 10, 2026
LTV:CAC tells you whether your business model actually works. If you spend more to acquire a customer than that customer is worth, you lose money on every sale, no matter how fast you grow.
It is one of the first metrics investors check for SaaS and subscription businesses. The ratio also reveals how aggressively you can invest in growth: a strong ratio justifies spending more on acquisition, while a weak one means you need to fix retention or pricing before scaling spend.
Divide LTV by CAC. LTV equals (ARPU times gross margin) divided by monthly churn rate. CAC equals total sales and marketing spend divided by new customers acquired.
Both sides must use the same basis. If LTV uses gross margin, CAC should be fully loaded to match. If you are comparing paid CAC specifically, use LTV calculated only from paid-channel customers rather than your whole customer base.
LTV is $2,133, based on $80 ARPU, 80 percent gross margin, and 3 percent monthly churn. CAC is $500. LTV:CAC equals $2,133 divided by $500, or 4.3:1.
This suggests healthy unit economics with room to increase acquisition spend, assuming the underlying cohorts are mature enough to trust the churn assumption.
Below 1:1 means you are losing money on every customer. Fix retention, pricing, or CAC before scaling further.
1:1 to 3:1 is marginal: improving but not yet ready for aggressive growth investment.
3:1 to 5:1 is the healthy target range for most SaaS businesses.
Above 5:1 signals strong unit economics, but can also point to under-investment in growth. Consider whether increasing spend would capture more market without hurting the ratio too much.
Using revenue-based LTV instead of gross-margin-based LTV, which inflates the ratio and makes economics look better than they are.
Comparing paid CAC with blended LTV, or the reverse, instead of keeping both sides on a matching basis.
Computing LTV from immature cohorts. If your oldest cohort is six months old, your LTV estimate is a projection rather than a measurement.
On your financials slide, show LTV, CAC, and the ratio together with payback period, and note the basis, meaning gross margin, and whether CAC is blended or paid. For example: LTV:CAC 4.3x on a gross margin basis, payback 12.5 months.
Use gross-margin-based LTV and a consistent CAC definition, either blended or paid.
Turn your metrics into a pitch narrative investors can follow.
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