Build the full preparation cost
Separate one-off and recurring expenses. Recruitment and immediate replenishment belong in the first layer. Expected income minus upkeep across the working war length belongs in the second.
Do not predict an entire campaign with one number. Choose a specific operation and a horizon after which the decision will be reviewed.
Set a treasury floor
A new front may require emergency recruitment, a diplomatic payment or recovery after an unexpected loss. The reserve preserves those options and does not need a direct return.
Choose the cash floor that must remain after preparation. Rerun with a higher floor when Patch 8.1 or the actual map increases the risk of active AI response. That remains a scenario, not a universal rating of the patch.
Count net flow across remaining turns
Use income after existing armies and commitments. Do not enter the peaceful treasury rate when confirmed new expenses begin before declaration.
Turns before war are a real resource. A building can be strong over the campaign and still conflict with the specific military deadline.
Decide before pressing the war button
When the treasury narrowly misses, delay one optional building or trim the first recruitment wave. When the gap is large, moving the date is more honest than assuming perfect sack income.
Save the scenario before declaring and review after the opening turns. Real deficit and replenishment length improve the next plan more than a universal war-chest recommendation.
Replace the baseline with your inputs and get an answer for your scenario.
Data note. Every numeric example is a transparent baseline scenario. It is not presented as official publisher data and can be recalculated in the linked tool.