The highest bid a keyword can afford is your average order value times its conversion rate times your target ACoS. If you pay more per click than that, the keyword will run above target. Enter your numbers to get your max bid.
max bid = AOV × conversion rate × target ACoS1 ÷ conversion rateIf one in ten clicks turns into an order, each order costs ten clicks. At a 30% target ACoS on a $30 order, you can spend $9 in ads per order, which is $0.90 per click across those ten clicks.
Use the conversion rate for the specific keyword once it has enough data (roughly 50 clicks; with fewer, one order swings the rate a lot), and fall back to the ad group or ASIN average until then. Amazon's CPC is usually below your bid because of how the auction prices clicks, so treat the result as a ceiling.
Placement multipliers (top of search, product pages) apply on top of the base bid, so lower the base bid if you add a large top-of-search adjustment.
Bid up to $0.90 per click to stay at or under a 30% ACoS.
Set a target ACoS and AdSpark's bid optimizer steers every keyword toward it, reviews search terms, and logs each change so you can reverse it. 14-day free trial.
Multiply average order value by conversion rate and by your target ACoS. For example, $40 × 12% × 25% = $1.20 maximum cost per click.
Use your ASIN's or ad group's average conversion rate until the keyword has enough clicks (roughly 50) to trust its own number, then recalculate. Fifteen to 20 clicks with no orders is enough to cut a bid, but not enough to set one precisely.
Amazon's auction typically charges close to what you needed to beat the next advertiser, not your full bid. Your bid is the most you're willing to pay.
Not always. Many sellers start below the max, then raise bids on keywords that convert and cut those that spend without orders. A continuous optimizer can make those changes every cycle.