Every Sponsored Products campaign has a bidding strategy setting, and many sellers leave it on whatever was chosen at launch. That setting decides whether Amazon can change your bid in each auction, and in which direction. It interacts with placement adjustments, which can raise bids further. Together they can make the bid you typed very different from the bid you pay.
This guide compares the three strategies, explains how placement adjustments stack on top, and gives a simple way to choose and test.
The three strategies
Dynamic bids, down only. Amazon lowers your bid in auctions it judges less likely to convert. It never raises it. Your keyword bid is a ceiling.
Dynamic bids, up and down. Amazon raises your bid in auctions it judges more likely to convert and lowers it in those it judges less likely. Amazon's documentation describes the increase as up to 100 percent for top of search and up to 50 percent for other placements.
Fixed bids. Amazon uses your bid as entered, plus any placement adjustment. No dynamic changes in either direction.
How Amazon PPC bidding works covers how the auction itself uses your bid.
Placement adjustments stack on top
Separately from strategy, you can raise bids by placement: top of search, rest of search, and product pages. Adjustments can be large, and they multiply with the strategy. A keyword bid with an up and down strategy and a high top of search adjustment can end up far above what you typed.
That is not a reason to avoid adjustments. It is a reason to check the placement report before setting them, and to know your effective maximum bid before you let a campaign run. Sponsored Products placements covers how to read placement data.
When down only fits
Down only is the safe default. It cannot raise your cost per click above your bid, and it trims bids in weaker auctions. It suits new campaigns where you are still learning conversion rates, broad and automatic campaigns that reach many loosely related searches, and any campaign where budget control matters more than reach.
The trade-off is that down only can under-deliver on your best keywords. If a keyword converts very well and you want more of the top of search placement, down only will not push for it.
When up and down fits
Up and down suits campaigns with a proven record: exact match keywords that convert above your account average and where top of search placement has shown a better conversion rate than other placements. In those campaigns, letting Amazon bid higher on the most promising auctions can bring more of the sales you want.
The risk is cost. On a campaign with weak conversion, up and down can raise spend without raising orders in proportion. Use it only where you have data that the extra exposure pays, and set the base bid a little lower to leave room for the increase.
Illustrative example: Harbor Kitchen moves three exact match campaigns for its best-selling knife set from down only to up and down, and lowers base bids slightly. Over four weeks, top of search impressions rise and ACoS holds near target. On a fourth campaign with weaker conversion, the same change raises ACoS, so Harbor switches it back.
When fixed bids fit
Fixed bids are useful when you need to know exactly what you are bidding. That includes tests where dynamic changes would muddy the result, campaigns run by rules or software that sets bids on its own schedule, and very low-bid discovery campaigns where you want a firm ceiling.
Fixed bids can lose auctions that dynamic strategies would have won, and can overpay in weak auctions that down only would have trimmed. They trade efficiency for predictability.
Strategy, schedules and rules together
Bidding strategy works auction by auction. It does not know that your account converts poorly at 3am or that a holiday is coming. Hour-of-day schedules and rules work on top of it. A schedule that lowers bids overnight lowers the starting point, and the strategy then adjusts from there.
If you use automation that changes bids, be aware of what the strategy will do to them. A rule that raises a bid on a campaign set to up and down is raising the base for a further dynamic increase. Bid adjustments by hour covers how hourly changes interact with campaign settings.
How to test a strategy change
Pick campaigns with enough volume to read results in a few weeks. Change one setting at a time. Note the date and the old setting. Compare cost per click, conversion rate, ACoS and total sales for at least two to four weeks before and after, and avoid windows that include events. If you can, change half of a group of similar campaigns and leave the other half as a control. Split testing in Amazon PPC covers the method.
Frequently asked questions
Which Sponsored Products bidding strategy is best?
There is no single best one. Dynamic bids down only is the safest default for most campaigns because it can only lower your bid. Up and down suits proven campaigns where you want more top-of-search exposure. Fixed bids suit tests and campaigns where you need precise control over cost per click.
How much can dynamic bids up and down raise my bid?
Amazon's documentation describes increases of up to 100 percent for top of search placements and up to 50 percent for other placements when the strategy is set to up and down. Placement adjustments are applied on top of that, so the effective bid can be higher still. Check the console help for the current limits.
Should I change bidding strategy during Q4 or a sales event?
Changing strategy right before an event makes it hard to tell whether results came from the event or the change. If you want to test up and down for an event, try it on a few proven campaigns a few weeks earlier, so you know how it behaves before traffic peaks.
Off Hours bid adjustments step bids on trailing ROAS within a cap you set, running on a 15-minute cadence alongside whichever bidding strategy each campaign uses. Start a free 14-day trial.