Amazon PPC Bid Calculator
Every keyword has a price above which it quietly stops making you money. Most sellers have never worked out theirs. Give this three numbers and you'll have yours.
Find your ceiling
Three of these come straight off your search term report. The fourth tells you whether you're already past the line.
This is a ceiling on what you can pay per click, not the number to type into the bid field. Placement multipliers and dynamic up-and-down bidding both lift the auction bid above your base bid, and they compound rather than add. Turn each into a factor (a +100% adjustment is 2x), multiply them together, and divide the ceiling by that. A +100% top-of-search adjustment alongside dynamic up-and-down bidding is 2x times 2x, so the base bid is a quarter of the ceiling, not half.
From your margin. Work out what's left of a sale after COGS, referral fees, and FBA. That number is the line where a sale earns you nothing. Enter a rough margin below, or work it out properly with the break-even ACoS calculator, which accounts for returns too.
This runs entirely in your browser. Nothing you type gets sent anywhere. If you'd rather not type at all, connect your account free and the numbers come from your own campaigns.
The Amazon PPC bid formula
One line of arithmetic, and most of the argument about bidding goes away. You've already decided what share of an order you'll hand to Amazon. Your conversion rate decides how many clicks it takes to earn that order. Put the two together and you know what a single click is worth to you.
Run it backwards if that lands better. A 12% conversion rate means about 8.3 clicks per sale. A $35 sale at a 26.4% target hands you $9.24 to spend. Spread $9.24 over 8.3 clicks and you get $1.11. Pay $1.50 instead and you aren't running a 26.4% ACoS anymore. You're running 35.7%, and nothing in Seller Central is going to tell you that this week.
The two numbers hiding inside it
Ad budget per order
What one sale can afford to spend on advertising. Conversion rate never changes this figure. It only decides how many clicks the money has to stretch across.
Break-even ACoS
A 33% margin puts break-even at a 33% ACoS. Above that line you're buying something other than profit. On a launch, that's a decision. On a mature ASIN it's usually an accident.
Where each number comes from
All four are sitting in reports you already have.
Target ACoS
Yours to choose, but anchor it on margin. Work out what survives COGS, referral fees, and FBA, then pick a target at or under that.
Selling price
What the shopper actually pays, coupons and promos included. A 20% coupon takes 20% off your ceiling at the same time.
Conversion rate
Orders divided by clicks in your search term report, for the exact thing you're bidding on. Ad traffic, not the listing's session conversion rate.
What you pay now
Spend divided by clicks over the last 30 days. What you're actually being charged, which is rarely the number you typed into the bid field.
What this can't see
The arithmetic is honest. Your inputs might not be. Five things routinely turn a correct calculation into the wrong bid.
Thin click volume
Fourteen clicks and one order reads as a 7.1% conversion rate. It isn't 7.1%. It's noise wearing a decimal point. Wait until one more order wouldn't swing the number much.
Repeat purchases
A consumable that sells five times a year to the same buyer is worth far more than its first order's margin. Bid on one order and you'll underbid every subscribe-and-save keyword you own.
Organic lift
Ads that push a listing up the rankings create organic sales that ACoS never gets credit for. That's the whole reason TACoS exists, and the reason launch bids sit above break-even on purpose.
Inventory position
The right bid on a SKU with eleven weeks of cover is the wrong bid on one that stocks out a week from Thursday. Check cover before you scale, not after.
Bid adjustments
Your base bid is not what you get charged. A top-of-search multiplier and dynamic up-and-down bidding both raise the auction bid, and they stack multiplicatively: +100% placement on top of +100% dynamic is 4x your base bid, not 2x.
One keyword at a time is the problem
This page does the math for one keyword, using numbers you typed in. You probably have a few hundred keywords, and their conversion rates move every week. Connect Amazon Ads and Seller Central and your AI assistant runs the same arithmetic across all of them from live data, then makes the changes you approve.
- Ask in plain English which keywords are bidding past their ceiling.
- Have the bid changes applied through AI once you've said yes.
- Put keyword rules on a schedule so converters get harvested and waste gets negated.
- Check inventory next to ad performance before you scale anything.
Frequently Asked Questions
Multiply three numbers: selling price, target ACoS, and conversion rate. A $35 product at a 26.4% target ACoS and a 12% conversion rate gives 35 x 0.264 x 0.12, or $1.11. The logic underneath it: 12 clicks out of every 100 turn into a $35 order, you have decided to spend 26.4% of that order on ads, so one order carries $9.24 of ad budget and that money has to cover roughly 8.3 clicks.
Start with your margin after COGS, referral fees, and FBA. That figure is your break-even ACoS, the point where a sale earns you nothing. Pick a target under it when you want every sale profitable on its own. Sit right at it when you are buying volume or defending a listing you cannot afford to lose. Go over it only when you have decided to pay for rank and reviews, and you know that is the trade you are making.
The conversion rate of the ads, not of the listing. In an Amazon Ads search term or targeting report that is orders divided by clicks for the keyword or ad group you are bidding on. Ad traffic converts differently from organic traffic, so the unit session percentage in Seller Central will hand you a ceiling that is wrong in one direction or the other.
Amazon's suggested bid is built from what other advertisers are paying for that placement. It knows nothing about your price, your margin, or how well your listing converts. When the suggestion sits well above your ceiling, that keyword is priced for a seller with a higher order value or a better conversion rate than yours, and buying it at the suggestion means buying it at a loss.
No. The number tells you what has to stay true for you to hit your target, given the conversion rate you entered. Real ACoS moves whenever conversion rate, order value, or the auction moves. A keyword with a dozen clicks has a conversion rate that is mostly noise. Treat the ceiling as a limit to bid against, then work it out again once that keyword has enough clicks for its conversion rate to mean something.
It is a ceiling on your cost per click, which is not the same as your bid. Amazon charges you the auction price, and a top-of-search or product-page placement multiplier, plus dynamic up-and-down bidding, both lift that above the base bid you set. They compound rather than add, so turn each one into a factor, where a +100% adjustment is 2x, multiply them together, and divide the ceiling by the result. A +100% top-of-search adjustment alongside dynamic up-and-down bidding is 2x times 2x, so a $1.00 ceiling means a base bid no higher than $0.25. The "what you're paying now" figure in the calculator is already a charged CPC, so that comparison is like for like.
Yes, and it stays in your browser. No account, no email, nothing you type gets sent to us. If you would rather stop typing numbers in by hand, that is what connecting your Amazon Ads and Seller Central accounts to Marketplace Ad Pros does.
Know the ceiling on every keyword you own
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