Note 03 · Cash & growth
When does your app pay back its acquisition cost?
Good things take time to add up.
Track cumulative contribution from an acquisition cohort. Payback is the first point when that contribution covers the cohort’s acquisition cost. A single LTV snapshot cannot tell you the exact day.
Follow the same users through time.
Acquisition spend usually arrives before the full return. A subscription may renew several times; ad revenue accumulates as people return. Payback measures how long it takes the acquired cohort to cover its acquisition cost.
For this note, use cumulative contribution: purchase and ad proceeds after deductions, minus the variable costs of serving the cohort. This gives a more useful operating comparison than gross billings.
RevenueCat’s discussion of LTV:CAC alternatives explains why fixed-age cohort snapshots and contribution deserve attention alongside lifetime estimates.
Three checkpoints tell a useful story.
Hypothetical cohort · $1,800 acquisition spend
- D30
- $1,200Not yet recovered
- D60
- $2,100First observed recovery
- D90
- $2,600Still above cost
First observed recovery: D60
Cumulative contribution from 1,000 installs. With monotonic growth, payback lies between D30 and D60; these checkpoints cannot identify the exact day. Later refunds or costs can reverse recovery.
Imagine 1,000 installs with a total acquisition cost of $1,800. These are illustrative observations, not industry benchmarks.
| Cohort age | Total | Per install | Cost covered? |
|---|---|---|---|
| D30 | $1,200 | $1.20 | No |
| D60 | $2,100 | $2.10 | Yes |
| D90 | $2,600 | $2.60 | Yes |
At the measured checkpoints, the cohort is below its acquisition cost at D30 and above it at D60. If contribution grows monotonically, payback happened between those checkpoints. The exact day requires a finer time series; interpolating a smooth line would be an assumption.
Refunds and later costs can push a cohort back below break-even. Check whether recovery is sustained, especially for products with material refund rates.
Revenue earned is not cash received.
A store or ad network may report proceeds before paying them out. Economic payback from your analytics and cash payback in your bank account can therefore happen on different dates.
Track payout schedules alongside invoices, ad bills, refunds, and cash reserves. A cohort can eventually make a positive contribution while the business runs short of cash funding the next cohort.
Annual subscriptions also collect money before you have delivered a year of service. Keep future delivery costs in the model when interpreting a fast early recovery.
Make the comparison repeatable.
- Group installs by acquisition period and channel.
- Record cumulative net proceeds and variable costs at consistent cohort ages.
- Compare with the same cohort’s acquisition spend.
- Record the first observed recovery, then check subsequent checkpoints.
- Compare the result with the cash runway and margin your business needs.
Our LTV calculator checks whether a cohort has covered acquisition at one chosen age. It does not estimate a payback day from a single snapshot.
Sources & further reading
Examples are hypothetical. They illustrate the method and do not represent Piiko results or industry benchmarks.