Amazon offers three fundamental approaches to bid management: manual, dynamic, and rules-based automation. Most accounts default to one without a clear thesis for why. Getting this right is one of the highest-leverage PPC improvements any account can make, and it is one of the first things a good Amazon agency reviews in a new account.
The Three Bidding Strategies Explained
Manual bidding means setting a fixed bid for each keyword or target. You have maximum control and visibility into exactly what each keyword costs. The tradeoff: static bids in a dynamic auction environment.
Dynamic bidding allows Amazon to adjust bids in real time based on conversion probability. "Down only" reduces bids when conversion is deemed less likely. "Up and down" also raises bids — by up to 100% above your set bid — when conversion is deemed more likely.
Rules-based bidding uses conditional logic to automatically adjust bids based on performance thresholds you define. For example: if ACOS exceeds 25% over the last 14 days, reduce bid by 10%.
When Manual Bidding Wins
- New campaigns and keywords: No historical data means dynamic bidding has nothing to learn from.
- High-value exact match keywords: Precise cost control matters when a keyword is already expensive.
- Low-traffic accounts: Under 50 clicks per week on a keyword is typically insufficient volume for dynamic adjustments to work reliably.
Dynamic Bid Scenarios and Pitfalls
"Down only" is a safe default for most mature campaigns. "Up and down" is where pitfalls live — Amazon's conversion probability model doesn't know your margin structure and can raise bids on clicks that convert above your breakeven ACOS. Before enabling "up and down", set a campaign-level budget cap and monitor ACOS and contribution margin daily for the first two weeks.
Rules-Based Automation
Rules-based bidding is the highest-leverage approach for accounts with sufficient data volume. Well-constructed rules: reduce bids on keywords exceeding target ACOS over a defined lookback window; increase bids on keywords below target ACOS with sufficient impression volume; always include minimum click thresholds before triggering adjustments.
The Hybrid Approach
The most effective structure uses all three simultaneously: manual bids for new campaigns and highest-value exact match terms; dynamic "down only" for mature campaigns; rules-based automation for the broad mass of active keywords. For how bidding fits into the broader campaign architecture, see our guide on Amazon advertising strategy. For the metrics to evaluate whether your bidding is working, see our post on Amazon PPC ROI measurement.
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