Dynamic Bids Down Only vs Up and Down on Amazon: Which to Use, and How to Test It

Written by the BidVentor Editorial Team. Reviewed by Adeel Imrani, founder of BidVentor (14 years growing a $2M beauty brand on Amazon, $30M+ ad spend). Last updated November 2026.

Quick answer

“Dynamic bids – down only” lets Amazon lower your bid when a click looks less likely to convert, but never raise it, so the bid you enter (plus any placement adjustment) is your ceiling. “Dynamic bids – up and down” lets Amazon also raise the bid, by up to 100% for all placements according to Amazon’s current guide, when a click looks more likely to convert. Use down only for new, unproven or low-margin campaigns, and for anything where you are still finding your break-even CPC. Use up and down only on campaigns that already convert above your target, with stock to support more sales, and lower the base bid when you switch so the doubled ceiling still sits under your maximum affordable CPC.

Key takeaways

• Down only can never cost more than your bid times your placement adjustment. Up and down can cost up to twice that.
• Placement adjustments apply first, and the dynamic increase applies on top. A $1.00 bid with +50% top of search can reach $3.00 under up and down.
• Set the ceiling from your own break-even CPC, not from the bid box. Under up and down, the bid you enter should be about half of the most you can afford per click.
• Up and down suits proven, in-stock, high-converting campaigns and deal periods. Down only suits launches, research and thin margins.
• Test one campaign at a time for at least 14 days, and judge it on profit per order and CPC, not ACoS alone.

What each setting does to your bid

Every Sponsored Products campaign has a bidding strategy that decides whether Amazon may change your keyword and target bids in each auction.

Dynamic bids – down only. Amazon reduces your bid in real time when it predicts the click is less likely to turn into a sale. It never raises it. You will often pay less than your bid, and lose some auctions you might have won at full price. This is the setting many accounts run on without ever having chosen it, because it is the common default on new campaigns.

Dynamic bids – up and down. Amazon raises your bid when it predicts a click is more likely to convert, and lowers it when a click looks weak. Amazon’s own guide is direct about the cost: with a $1.00 bid, “we can increase this bid by up to 100%, so that would be a maximum of $2.00 for all placements,” and it tells advertisers to be “prepared to potentially spend double the amount of the bid you input.”

Fixed bids. Amazon uses the bid you set, with no automatic change. It is the cleanest setting for testing, because results reflect your bids alone. We compare all three in our dynamic vs fixed bids overview; this guide goes deeper on the choice most sellers actually face, which is down only or up and down.

Older guides say up and down was capped at 100% for top of search and 50% for other placements. That was the original rule. Amazon’s current guide says up to 100% for all placements, so plan your budget on the larger figure.

How placement adjustments stack with dynamic bids

This is where most surprise CPCs come from. Placement adjustments (top of search, rest of search and product pages) raise your bid by a percentage when your ad competes for that placement, up to 900%. They apply first. The dynamic increase then applies to the adjusted bid.

The simple formula for the most you can pay on a click is:

Maximum bid = base bid × (1 + placement adjustment) × (1 + dynamic increase)

The dynamic increase is up to 100% under up and down, and zero under down only or fixed. Here is what that looks like for a $1.00 base bid:

Setting	Top of search adjustment	Highest possible bid at top of search
Down only	0%	$1.00
Down only	+50%	$1.50
Up and down	0%	$2.00
Up and down	+50%	$3.00
Up and down	+100%	$4.00

A seller who sets a $1.00 bid, a +100% top of search adjustment and up and down has agreed to pay up to four times the number they typed. That only pays if top of search clicks convert well enough to earn it.

Start from the most you can afford per click

Before you pick a strategy, work out your maximum affordable CPC for the product:

Max CPC = price × conversion rate × target ACoS

Take a $30 product that converts at 10% of clicks, with a 30% target ACoS. The most you can pay per click and still hit target is $30 × 0.10 × 0.30 = $0.90. Our guide to working out your max CPC walks through the full method, including break-even.

Now set the bid so the strategy’s ceiling lands at or under that $0.90:

• Down only, no placement adjustment: bid up to $0.90.
• Up and down, no placement adjustment: bid about $0.45, because Amazon may double it.
• Up and down with +50% top of search: bid about $0.30, because $0.30 × 1.5 × 2 = $0.90.

These are illustrative numbers. The point is the habit: whenever you switch a campaign to up and down, cut the base bid at the same time, or your real CPC can jump overnight while every keyword bid still looks “the same”.

When down only is the better choice

Down only is the safer setting when you cannot yet prove that a higher bid pays back:

• New launches and research campaigns. You do not know the conversion rate yet, so you do not know the max CPC.
• Thin margins. If your break-even ACoS is 20% or less, there is little room for clicks that cost double.
• Broad and auto campaigns. These pick up loose matches. Down only lets Amazon pull back on weak queries while capping the strong ones at your bid.
• Low stock. If you are close to running out, paying more to win more sales only brings the stockout forward and can hurt rank later.
• Products with a conversion problem. If clicks are not turning into orders, a higher bid will not fix it. See our guide on PPC clicks but no sales before you raise anything.

When up and down is worth it

Amazon recommends up and down when your objective is sales, you want top of page placements, the campaign already performs well, or the ASINs have excess inventory or a deal. We agree, with one condition: the campaign must already convert above your target on a meaningful number of clicks.

Good candidates usually look like this:

• Exact match campaigns on proven terms, especially your own brand terms and your best non-brand converters.
• ACoS well under target for at least two to four weeks, so there is room to pay more per click.
• Healthy stock, with enough inventory to cover a sales lift for the next month or more.
• Deal and event periods, when conversion rates rise and top of page placements matter more. Switch back after the event ends.

A 14-day test to choose per campaign

You do not need to guess. Run a simple, controlled test on one campaign at a time:

1. Pick one proven campaign. Choose one that has converted steadily for a month, with enough daily clicks to read a result in two weeks.
2. Record a 14-day baseline. Note impressions, clicks, CPC, conversion rate, orders, ACoS and top of search impression share where your reports show it.
3. Switch to up and down, and halve the base bids. That keeps the highest possible CPC where it was before. Leave placement adjustments, budgets and targets alone so you change one thing only.
4. Run for 14 days. Allow a few extra days for attribution to settle before you judge the last week.
5. Compare on profit, not just ACoS. Did orders rise? Did CPC rise faster than conversion rate? Work out profit per order after ad cost for both periods.
6. Keep, revert or adjust. If orders rose and profit per order held, keep it. If CPC rose but orders did not, go back to down only. If results are mixed, try raising the base bid in small steps under up and down instead.

Amazon itself suggests reviewing bids about every two weeks and limiting changes while testing.

Four mistakes we see with dynamic bidding

1. Switching to up and down without lowering bids. This is the most common one. The keyword bids look unchanged, but the real ceiling has doubled.

2. Stacking a large placement adjustment on top. A +100% top of search adjustment plus up and down means up to four times the base bid. Use the placement report to confirm top of search actually converts better before you push both levers.

3. Judging the result in three days. Dynamic bidding needs volume. A few days of data tell you very little, especially on low-traffic campaigns.

4. Blaming the bid strategy for a listing problem. If ACoS rises across many terms at once while CPC is steady, the issue is usually conversion: price, reviews, Buy Box or the listing itself. We explain this pattern in how bid changes affect impressions.

How BidVentor helps with bids and bidding strategy

The BidVentor PPC tool connects to your Amazon Ads account through the Amazon Ads API (BidVentor is a verified Amazon Ads partner), or works from your bulk files if your team prefers. It shows which targets are bid above what they can afford, search terms that spend without orders, missing negative keywords, and budgets that need attention. Each recommendation shows the metrics behind it, including CPC, conversion rate, ACoS, ROAS and spend, so you can check whether a campaign is a good candidate for up and down before you switch. The PPC tool carries a 4X ROAS guarantee that applies to PPC only, and terms apply.

When the problem is conversion rather than bids, Buyer Blueprint reads all reviews for your ASIN or a competitor’s and shows why people buy and what nearly stopped them. Listing Genius COSMO turns that buyer language into a title, bullets and description built for Amazon’s COSMO algorithm and Rufus, so the clicks you pay for are more likely to turn into orders.

You get one free analysis after you sign up, which is a quick way to see which of your campaigns can afford a higher ceiling.

Frequently Asked Questions

What is the difference between dynamic bids down only and up and down?

Down only lets Amazon lower your bid when a click looks less likely to convert, but never raise it. Up and down lets Amazon also raise your bid, by up to 100% under Amazon’s current guide, when a click looks more likely to convert. Down only caps your cost at your bid; up and down can double it.

Is dynamic bids down only good for new campaigns?

Usually, yes. On a new campaign you do not yet know the conversion rate or your affordable CPC, so it makes sense to cap clicks at your bid. Move proven exact match terms to up and down later, once they have converted above target for a few weeks.

How much more can I pay with dynamic bids up and down?

Up to twice your adjusted bid. Placement adjustments apply first, then the dynamic increase. A $1.00 bid with a +50% top of search adjustment can reach $1.50 under down only and $3.00 under up and down.

Which is better for ACoS, down only or up and down?

Down only usually gives a lower or steadier ACoS, because it never pays more than your bid. Up and down can bring more sales and better placements, sometimes at a higher ACoS. Judge it on profit per order and total orders for the product, not on ACoS alone.

Sources and further reading

• Amazon Ads guide to dynamic bidding (up and down) for Sponsored Products.

Related guides

• Dynamic vs fixed bids: the full strategy overview
• How to work out your max CPC
• How bid changes affect impressions

About the reviewer

Adeel Imrani is the founder of BidVentor. He spent 14 years growing a $2M beauty brand on Amazon and has managed $30M+ in ad spend. Read more on his author page.

How we make this content

These guides are written by the BidVentor Editorial Team and reviewed by Adeel Imrani. Where we cite Amazon features or numbers, we link to Amazon’s own documentation. We update guides when Amazon’s tools or our guidance change, and we describe BidVentor’s features as they work today. See our methodology, or contact us with corrections.