Fixed Bid
Fixed Bid is the Sponsored Products bidding strategy in which Amazon submits your base bid unchanged to every auction — no dynamic shading up or down. It is the only strategy that gives the operator full control of the bid; everything else delegates control to Amazon's CVR-prediction model.
Fixed Bid is one of the three Sponsored Products bidding strategies, alongside Dynamic Bids – Down Only and Dynamic Bids – Up and Down. With Fixed Bid, Amazon submits your base bid unmodified into every auction — no shading down on low-CVR predictions, no shading up on high-CVR predictions. The bid you set is the bid the auction sees (before placement modifiers, which still apply).
Fixed Bid is the strategy of last resort and first principle: the only one that hands the operator full control of the bid input. Everything else lets Amazon's CVR-prediction model move the bid by up to 100% in either direction.
The three strategies in one table
| Strategy | Down-shading | Up-shading | Use case |
|---|---|---|---|
| Down Only | 0–100% | None | Default for most campaigns; safe efficiency |
| Up and Down | 0–100% | 0–100% | Scaling campaigns where you want Amazon to chase high-CVR auctions |
| Fixed Bid | None | None | Brand-defence, controlled testing, scenarios where Amazon's CVR signal is unreliable |
See Dynamic Bidding for the mechanics of shading.
When Fixed Bid is correct
- Brand defence on your own brand terms. Branded queries convert reliably regardless of Amazon's prediction; Down Only often under-bids them. Fixed Bid keeps you in the auction at the price you set.
- New campaign with no CVR history. Amazon's shading model has nothing to predict from in the first 30–100 clicks; Down Only can suppress impressions to the point of starving the campaign of data.
- Controlled testing. Measuring the lift from a creative or photography change — you want bid noise removed from the experiment.
- Highly seasonal queries entering peak. When CVR is about to jump but Amazon's prediction is lagging, Fixed Bid avoids the shading lag.
- Rule-based bidding tools that manage the bid externally. External bid management (rule-based bidding) handles dynamic adjustment itself; Amazon's shading would interfere.
When Fixed Bid is wrong
- Mature campaigns with stable CVR signals. Amazon's shading is genuinely useful here; Fixed Bid leaves efficiency on the table.
- High-volume generic auto / broad campaigns. Without down-shading, low-CVR placements consume budget that Down Only would have suppressed.
- Cost-sensitive operators not actively watching the campaign. Fixed Bid is unforgiving — over-bid and the spend lands fast.
The transition pattern
A common lifecycle for a Sponsored Products keyword:
- Fixed Bid for the first 60–100 clicks to gather clean CVR data unaffected by shading.
- Down Only once CVR is established and stable.
- Up and Down when the goal shifts to scaling impression share against confirmed CVR.
The operator who runs Up and Down on day 1 of a new campaign hands Amazon a CVR prediction problem it cannot yet solve, and the resulting bid noise pollutes early data.
Fixed Bid does not disable everything
Fixed Bid disables dynamic shading only. The following still apply:
- Placement modifiers (top-of-search, product pages, rest-of-search).
- Budget caps — the campaign still stops at daily budget.
- Eligibility filters — the ad still has to be eligible to enter the auction.
- Relevance scoring in the auction itself (Amazon's internal model that affects rank).
Common mistakes
- Defaulting to Down Only on launch. Starves new campaigns of data; Fixed Bid for the first weeks is often better.
- Running Fixed Bid forever on mature campaigns. Hands free efficiency to competitors using Down Only effectively.
- Forgetting placement modifiers still apply. Fixed Bid + 200% ToS modifier = 3× the bid at top-of-search.
- Mixing Fixed Bid with external rule-based tools that also expect dynamic strategies. Read the tool's docs — strategy mismatches cause bid loops.