ACoS stands for Advertising Cost of Sale. As detailed in our Beginner’s Guide to Amazon PPC, this is a calculation of how much you’re spending on Amazon advertising. This figure is then divided by your attributed promoted product sales. Accurately calculating your ACoS allows you to understand how your Amazon sponsored ad campaigns are performing. It’s also handy for figuring out whether you’re spending too much on a specific campaign – if your ROI isn’t ideal, then something needs to be done about it.