For any given click, our systems are designed to charge you only the minimum amount required to attain the ad's position, based on your ad’s quality and bid. You’ll never be charged more than your bid and, in some instances; your costs may be lower than your actual bid.
In general, your bid should be set to help you achieve your marketing goal, such as positive ROI or an increase in traffic volume, and you should never bid more than you can afford to pay.