Target ACOS and max CPC.

Worked example

Margin 40%, target profit 10%: target ACOS 30%. Price $25 and 10% conversion: 10 clicks per order, maximum ad cost per order $7.50, so the highest bid is $0.75. At break-even (40%), it is $1.00.

How it works

Target ACOS = margin - target profit. Margin is before ad spend, so enter it after product cost, fees and fulfillment.

Max CPC = ACOS x price x conversion rate. Each order needs 1 / conversion rate clicks, and ACOS x price is the most you may spend per order, so the most per click is their ratio.

Use your own conversion rate (orders / clicks) from the same campaign or listing. A bid above this ceiling does not always lose money on every click, since conversion varies, but sustained spend above it pushes ACOS past your target.

ACOS is defined by Amazon Ads as ad spend divided by ad revenue; the rest is arithmetic on your inputs.

Source (opened 2026-10-18): What is advertising cost of sales (ACOS)? Calculation and tips - Amazon Ads. Everything else is arithmetic on your inputs.

Inputs are user-entered figures. Results are planning estimates, not financial advice or a forecast. This tool is not affiliated with or endorsed by Amazon. Everything runs in your browser. Nothing you type is sent or stored.

FAQ

How do I turn a target ACOS into a bid?

Multiply the target ACOS by the selling price and by the conversion rate. The result is the highest cost per click that still meets the target on average.

Which conversion rate should I use?

Orders divided by clicks over a recent period for the same product and campaign type. Low-click data is noisy, so use a longer window.

Why does a lower conversion rate lower my max bid?

More clicks are needed per order, so each click must cost less to keep the cost per order under the same ceiling.

Does this include the cost of returns?

No. Include expected return cost in your margin if it applies to you.