Buried in every Amazon campaign is a setting most sellers pick once, ignore forever, and never connect to their results: the bidding strategy. Dynamic or fixed, up-and-down or down-only — this single choice quietly controls how Amazon spends your money in every auction. Get it wrong and you're either overpaying for clicks or missing sales you'd have won.
Here's what each bidding strategy actually does, when to use which, and how to stop leaving this decision on autopilot.
1. The Setting Most Sellers Ignore
When you create a campaign, Amazon asks how you want it to bid — and most sellers click past it without a thought. But this setting determines whether Amazon sticks to the exact bid you set or adjusts it in real time based on how likely a click is to convert.
That's not a minor detail. It changes your effective cost per click on every single auction, which means it shapes your ACoS and your sales volume directly. Two sellers with identical keywords and identical bids can get completely different results purely from this choice. It deserves a deliberate decision, not a default.
The point: Your bidding strategy controls how your bid behaves in every auction. Choosing it on purpose is free performance most sellers skip.
2. Dynamic Bidding — Down Only
With "dynamic bids — down only," Amazon lowers your bid in real time when it predicts a click is unlikely to convert. It never raises your bid above what you set. This is the most conservative, budget-protective option.
It's the safest place to start, especially for new campaigns or new products where you don't yet know what converts. You're protected from overpaying on low-probability clicks, and your bid is effectively a hard ceiling. The trade-off is that you may miss high-value auctions where bidding up would have won a sale you'd have happily paid more for.
The takeaway: Down-only is your default for launches and testing — it caps risk while you learn what's worth paying for.
3. Dynamic Bidding — Up and Down
"Dynamic bids — up and down" lets Amazon both lower your bid on weak auctions and raise it — by up to 100% in some placements — when a click looks highly likely to convert. You're trusting Amazon's prediction engine to chase the best opportunities aggressively.
This can be powerful on proven keywords with strong conversion history, where bidding up to win a high-intent shopper is genuinely worth it. The danger is that your costs can spike beyond your set bid, so it's not for unproven terms or tight budgets. Use it where you already have data showing the keyword converts well and the extra spend pays off.
The takeaway: Up-and-down is an accelerator for proven winners, not a setting for keywords you're still testing.
4. Fixed Bidding
"Fixed bids" means exactly that — Amazon uses your bid as-is, every time, with no real-time adjustment up or down. What you set is what you pay (up to that amount), regardless of how likely the click is to convert.
Fixed gives you maximum predictability and control, which makes it useful for specific tests where you want to hold a variable constant, or for keywords where you trust your own judgment over Amazon's algorithm. The downside is you lose Amazon's conversion-probability intelligence entirely — you'll keep paying full bid even on auctions the algorithm would have flagged as poor. Most sellers find down-only outperforms fixed for general use.
The takeaway: Fixed bids trade Amazon's intelligence for total predictability — handy for controlled tests, rarely the best default.
5. Placement Adjustments Multiply Everything
Bidding strategy doesn't work alone. Amazon also lets you boost bids for specific placements — top of search, rest of search, and product pages — by a percentage. These placement multipliers stack on top of your bidding strategy, and top-of-search placement often converts dramatically better.
The smart move is to check your placement reports and see where your sales actually come from. If top-of-search is converting well, a placement boost there can win premium positions profitably. But understand the math: an up-and-down strategy combined with a big top-of-search multiplier can send your effective bid far above your base number, so layer these adjustments knowingly, not blindly.
The takeaway: Placement multipliers compound with your bidding strategy. Use placement data to boost where you convert — and watch the combined effect on cost.
6. Match the Strategy to the Campaign's Job
There's no single best bidding strategy — there's the right one for what a campaign is trying to do. A brand-new launch protecting a tight budget wants down-only. A proven, profitable keyword you want to scale aggressively might justify up-and-down with a top-of-search boost. A controlled test wants fixed.
The mistake is applying one strategy across your whole account out of habit. As campaigns mature and you learn what converts, your bidding strategy should evolve with them — typically starting conservative and getting more aggressive only where the data earns it. Revisit the setting as part of your regular optimization, not just at setup.
The takeaway: There's no universal best strategy — match it to each campaign's goal and revisit it as the campaign matures.
The Bottom Line
Your bidding strategy is a lever hiding in plain sight. Down-only protects you while you learn, up-and-down accelerates proven winners, and fixed gives you control for tests — and placement multipliers compound on top of all three.
Stop accepting the default. Start new and unproven campaigns on down-only, graduate winners to more aggressive strategies as the data justifies it, and use placement data to push where you actually convert. It's a few clicks that quietly shape every auction you enter.