No fixed percentage of revenue is a safe Amazon PPC budget rule. Budget depends on seller-provided margins, inventory, campaign history, objectives, risk limits, and the period being measured. This framework is for documenting those inputs and approving changes; it is not a forecast of payback, ranking, or ACoS.
Build a client-scoped budget ledger
For each SKU or agreed portfolio group, record the current price and costs, break-even ACoS formula, inventory cover, campaign type, source-report period, current budget, proposed limit, business reason, and review date. Keep seller data isolated to that client. Do not derive a target from pooled data from other sellers.
Launch and discovery
A launch has limited history, so the client should approve a bounded test budget and loss limit before spend begins. Search-term and placement evidence should be reviewed as it becomes statistically useful for that account. Amazon controls ad delivery and organic placement; traffic or spend does not guarantee indexation, ranking, reviews, or later payback.
Growing and mature catalogs
For established campaigns, separate branded and non-branded demand and review budget caps by SKU rather than relying on one account-wide percentage. Increase, hold, or reduce a budget only when the seller's current margin, inventory, placement, and search-term evidence support the decision. Historical efficiency can change with price, competition, seasonality, and inventory.
Defensive and seasonal decisions
A competitor entry, promotion, or seasonal event may justify a temporary change, but the amount and duration must be written for the specific client. Define the stop condition and the evidence needed to extend the test. Do not describe a temporary budget increase as guaranteed retention or future organic growth.
BFarm review sequence
- Review seller-authorized bulk, search-term, placement, inventory, and cost inputs.
- Calculate and disclose the break-even ACoS formula, assumptions, source periods, and as-of dates.
- Write proposed budget and bid changes with a reason and measurement window.
- Obtain client approval before applying changes.
- Compare the next suitable period and report the result without treating correlation as proof of causation.
There is no universal stabilization period. The review window depends on traffic, attribution, campaign change, seasonality, and data quality. Outcomes are account-specific and are not guaranteed.
See the BFarm methodology, the negative-keyword review framework, and the Advertising Optimization service.