“In the US on Android, anywhere from $200 to $300 a day. On iOS it's got to be more significant — at a minimum about $500 a day to see if you can get enough traffic and then actually have something to do with that traffic to be able to make adjustments.”

Minimum viable UAC budgets: $300/day Android, $500/day iOS — anything less gives unusable data

iOS campaigns cost significantly more than Android because CPMs and install costs are higher. These figures from someone who saw thousands of accounts at Google are the true floor for getting the algorithm enough signal to optimize — not arbitrary recommendations. Below these thresholds the algorithm runs in permanent learning mode.