With vCPM bidding, you bid for your ad based on how often it appears in a viewable position on the page. You set the max amount you want to pay for viewable ads.
How to use vCPM bidding
You set the highest amount you want to pay for each 1,000 viewable ad impressions. We call this the maximum vCPM bid, or just "max viewable CPM." The higher your max viewable CPM, the greater the chance that your ad will appear. The system will charge you only what is needed to place your ad above the next-highest ad, and only charge if the ad became viewable.
Viewable CPM bidding
With viewable CPM (vCPM) bids, you only pay when your ad is able to be seen by potential customers. This means you're bidding on the actual value of your ad appearing in a viewable position on a given placement.
Keep in mind that using a higher vCPM bid than your CPM bid is usually more effective for winning these more valuable types of impressions.
Your max viewable CPM bid may win different levels of impressions at different prices than previous max CPM bids. Because you don’t pay for impressions that were not viewable, you may want to increase your max viewable CPM bid to achieve the same level of spend and traffic volume.