900 in month one
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ACQUISITION / ATTRITION / TARGETS / SCENARIOSModel the list.
Model the list.
Expose the levers.
Project active subscribers with channel-specific acquisition, explicit monthly losses, a comparable improvement scenario, and a target you can solve backward.
- Monthly ledger
- Target solver
- Local calculation
18-MONTH BASELINE
Baseline reaches the target in month 11.
16,200 gross acquired − 2,684 gross lost across 18 months. Calculations preserve fractional expected counts.
23,516projected active+13,516 from start
This is a deterministic flow model, not a promise.
It assumes entered rates continue, categories do not overlap, and each month's attrition applies to the opening active list before new subscribers arrive.
0.90% of opening active each month
Constant acquisition to reach 18,000
+2,796 versus baseline
ACTIVE LIST TRAJECTORY
Baseline, improvement scenario, and target.
Baseline Improvement scenario Target
TARGET SOLVER
Baseline reaches 18,000 in month 11.
Desired active subscribers at or before month 18.
Closed-form result using current attrition and month-start timing.
Relative change from 900 current monthly acquisition.
Scenario: month 9.
LONG-RUN CONTEXT
Constant inflow and proportional loss converge toward a fixed point.
100,000constant-flow equilibrium
At constant month-one acquisition of 900 and 0.90% monthly attrition, the mathematical equilibrium is 100,000 active subscribers.
ACQUISITION CONTRIBUTION
See which channel supplies the growth.
CHANNELMONTH 1MONTHLY CHANGEHORIZON TOTALSHARE
72.2%
27.8%
MONTHLY LEDGER
Opening list, inflow, outflow, and closing list.
MONTHOPENINGACQUIREDLOSTNETCLOSINGSCENARIO
MODEL REVIEW
Assumptions are internally consistent.
Loss components must be mutually exclusive
Deduplicate people who could appear in multiple source events before adding component rates.
Improvement scenario creates measurable separation
2,796 more active subscribers by month 18 under the entered lift and attrition reduction.
Displayed people are rounded; calculations are not
The recurrence preserves fractional expected counts to avoid compounding display-rounding error.
PLANNING HANDOFF
Export exact assumptions, monthly flows, scenarios, target math, and model boundaries.
THE FLOW MODEL
Active list size is opening balance, minus losses, plus acquisition.
The model keeps gross acquisition and gross attrition visible. A positive net number can still hide excessive loss, while a stable list can require substantial acquisition merely to replace people who leave.
CLOSING ACTIVEopening active−monthly losses+new subscribers
ORDER OF OPERATIONS
Attrition applies to the opening list before monthly acquisition.
New subscribers enter at the end of the modeled month and first face attrition in the next month. Real systems operate continuously, so the monthly result is an approximation whose value depends on consistent timing across baseline and scenario.
SOLVE BACKWARD
The target solver finds constant monthly acquisition under current attrition.
It uses the closed form of the same recurrence shown in the ledger. Channel growth assumptions are excluded from this particular answer so the result remains a clear constant-flow requirement.
FIXED POINT
Equilibrium exists only when acquisition and attrition assumptions are constant.
With constant monthly acquisition A and loss fraction c, the fixed point is A ÷ c. When any acquisition channel grows or declines each month, the acquisition flow moves and a single fixed equilibrium no longer describes the model.
COMMON QUESTIONS
What should starting active subscribers include?+
Use people who are currently contactable for the modeled stream and consent scope. Exclude historical contacts that are unsubscribed, suppressed, or otherwise ineligible.
Can I add unsubscribe, bounce, and cleanup rates together?+
Only when the categories are mutually exclusive in your source data. If one person can appear in multiple components, deduplicate the terminal loss first.
Why can the list grow while gross attrition is high?+
Acquisition can mask the outflow. That is why the tool reports gross acquired and gross lost separately from net change.
Is equilibrium a maximum list size?+
It is a fixed point under constant acquisition and proportional attrition, not a hard cap. Change either flow and the fixed point changes.
Are projected subscriber counts exact people?+
No. Calculations preserve fractional expected counts and the interface rounds for planning. Actual people and events are discrete and variable.