Active-payer stock and cumulative acquisition economicsMonths on x-axis; payers on left scale; currency in ledger
Marketing & Advertising
App Acquisition Forecast Calculator
Roll an app-acquisition plan month by month instead of multiplying one launch month by the horizon. The calculator grows paid and organic install streams independently, carries the active-payer stock through monthly retention, adds new payers, prices paid installs at CPI, and produces an exact monthly ledger. It supports capacity, cash, and growth decisions while making the difference between acquisition flow and retained payer stock explicit.
Input evidence: use paid and organic install definitions from one analytics source, a matured install-to-paid cohort, and payer retention measured on the same billing event. Growth is a scenario assumption, not a measured guarantee.
Ending active payers—
Cumulative new payers—
Cumulative net payer value—
Paid acquisition spend—
Forecast net contribution—
Peak active-payer month—
Payer stock-flow forecast
Track retained payer stock, new cohort inflow, value, and paid acquisition month by month
The stacked area separates surviving payer stock from new payers; the ledger preserves exact cohort arithmetic.
| Month | Paid installs | Organic installs | Opening payers | Retained payers | New payers | Closing payers | Net value | Paid spend | Net contribution |
|---|
How to use
Build a payer forecast from compatible acquisition cohorts
- Enter paid and organic installs from one measurement rule.
- Use a matured install-to-paid conversion.
- Estimate monthly payer retention from recurring cohorts.
- Set an explicit install-growth scenario and horizon.
- Read stock, value, spend, and contribution together.
Forecast fundamentals
Five stocks and flows shape the result
Paid installs
Installs priced at entered CPI.
Organic installs
Unpriced here but not necessarily incremental or free.
New payers
Current installs converted under the cohort rate.
Retained stock
Prior active payers surviving one month.
Net payer value
Monthly contribution after service and platform costs.
Result interpretation
Ending stock does not replace cohort economics
Ending payers show scale at the horizon; cumulative new payers show acquisition throughput. Value and spend expose economics, net contribution combines them, and peak month reveals whether decay overtakes acquisition.
Calculation method
Retain opening stock, then add the current cohort
Each month grows installs, converts total installs to new payers, retains the opening payer stock, and values the closing stock.
Cohort compatibility
Rates from different app versions create a fictional path
Separate platform, country, channel, price plan, and app-version cohorts when their conversion or retention differs materially.
Organic boundary
Organic volume may contain paid spillover and baseline demand
The model does not assign an acquisition cost to organic installs or claim they were caused by media.
Growth and saturation
Constant growth is a scenario, not an auction-response curve
At scale, CPI, audience quality, fraud, and conversion can deteriorate. Run separate growth paths instead of extending one rate indefinitely.
How to read the visualization
Distinguish surviving payer stock from new inflow
Month is horizontal and active payers are vertical. The lower area is retained opening stock and the upper layer is new payers. Install growth and conversion change inflow; retention changes the surviving base. The display is misleading when a rising area is read as healthy economics even though CPI exceeds net payer value.
Detailed calculation process
Formula and intermediate steps: Propagate installs, payers, value, and spend
1. Iₜ = I₁(1+g)ᵗ⁻¹
2. Nₜ = (Pₜ+Oₜ)c
3. Rₜ = Aₜ₋₁r; Aₜ = Rₜ+Nₜ
4. Vₜ=Aₜv; Sₜ=Pₜ×CPI
5. Cₜ=Vₜ−Sₜ
In plain language, grow the install streams, convert the current cohort, retain prior payers, and compare monthly net payer value with paid acquisition spend.
- Pₜ, Oₜ
- paid and organic installs; installs/month
- g
- monthly install growth; decimal
- c
- install-to-paid rate; decimal
- r
- monthly payer retention; decimal
- Aₜ
- closing active payers; users
- v
- net monthly value; currency/user-month
Default substitution and reconciliation
Month 1 new payers=(42,000+16,000)×6.8%=3,944. Month 2 opening stock retains 3,944×82%=3,234 before the grown install cohort is added. Every row reconciles closing payers to retained opening plus new payers. Final check: every closing payer balance equals retained opening payers plus new payers, and the summed monthly value minus summed paid spend matches the forecast net contribution result card.
Evidence guidance
Reconcile product analytics, billing, and media
- Remove reinstalls and fraud consistently.
- Mature conversion and retention windows.
- Use net payer value after refunds.
- Document organic classification loss.
Limitations
The forecast is deterministic and cohort-average
It excludes channel mix, delayed conversion, reactivation, plan migration, annual billing, seasonality, CPI response, uncertainty ranges, and lifetime-value tails.
Glossary
App forecast terminology
- Payer stock
- Active paying users at a point in time.
- Cohort inflow
- New payers added during a month.
- Retention
- Fraction of prior stock remaining active.
- Organic install
- Install not priced to paid media here.
- Net payer value
- Monthly contribution per active payer.
- Stock-flow reconciliation
- Closing stock equals retained opening plus inflow.
Practical cases
Growth and retention imply different interventions
Fast installs, weak retention
The payer area plateaus despite rising acquisition, so product retention work precedes media expansion.
Stable installs, improving value
Active stock compounds and contribution turns positive; the team tests measured channel expansion rather than assuming constant CPI.
Important note
Before relying on this result
The forecast excludes channel mix, auction saturation, delayed conversion, refunds, plan changes, reactivation, seasonality, cohort-specific retention, uncertainty, and cash collection timing unless reflected in the inputs.
Additional App Acquisition Forecast Calculator questions
Why is retention applied to the opening payer stock?
It models surviving payers before the current month's new payer inflow is added.
Are organic installs truly free?
No. They are unpriced at paid CPI in this model but can depend on brand, ASO, referrals, and product investment.
Can monthly retention exceed 100 percent?
No. Expansion should be represented as value or payer inflow, not as survival above 100 percent.
Does the forecast include uncertainty?
No. It is a deterministic path; create separate low, base, and high assumptions when uncertainty matters.