LTV vs. CAC: what can you afford to spend?

First, make the denominators match.

LTV and acquisition cost only make sense together when they describe the same population. An install, an activated user, and a paying customer are three different denominators.

Suppose a campaign spends $1,800, acquires 1,000 installs, and eventually converts 100 of those people to paying customers. Its media cost per install (CPI) is $1.80. Its media acquisition cost per payer is $18. Neither number includes creative production or agency costs.

Compare the first number with value per install. Compare the second with value per acquired payer. Never compare payer LTV with CPI; that silently leaves out the cost of acquiring non-payers. AppsFlyer’s acquisition guide gives the underlying cost and value definitions.

Build a spending ceiling from contribution.

Continue with the hypothetical cohort in our LTV note: 1,000 installs generate $3,000 in net proceeds and incur $400 in variable costs by D90.

At $1.80 in acquisition cost per install, $0.80 remains by D90, or $800 across the cohort. At $2.60, acquisition consumes the entire contribution. At $3.00, the cohort is $400 short after variable costs, even though net proceeds match the advertising bill.

That $2.60 is an observed break-even ceiling for this cohort and window, before fixed costs and profit. It is not a recommended bid. Leave room for overhead, measurement uncertainty, and the return you need.

Be explicit about what acquisition costs include.

For a campaign comparison, you might start with media spend alone. For a business decision, add attributable creative, agency, and other acquisition expenses. Label the result so the two versions do not get mixed.

Keep organic users separate when assessing a paid campaign. Otherwise, organic revenue can make the campaign look more efficient than the paid cohort really is. Use consistent attribution windows and investigate large disagreements between ad platforms and purchase records.

Before increasing spend, check the next cohort.

A historical average does not guarantee the same result at a higher budget. New countries, audiences, creatives, and subscription plans can change both acquisition cost and value.

Compare mature cohorts at the same age, then inspect how quickly they recovered their cost. A ratio can look attractive while leaving you waiting months for the money. There is no universal LTV:CAC target that makes every mobile app healthy.

Use the cohort calculator to check the units. Then look at acquisition payback before choosing a budget.