Important: This article only contains information provided by Google.
Published on Thursday, May 14, 2020 • Updated on Thursday, February 3, 2022
According to Google, if an AD exceeds a total size of 4MB and there is no user interaction, it will be blocked.
Heavy Ad criteria
An ad is considered heavy if the user has not interacted with it (for example, has not tapped or clicked it) and it meets any of the following criteria:
Uses the main thread for more than 60 seconds in total
Uses the main thread for more than 15 seconds in any 30-second window
Uses more than 4 megabytes of network bandwidth
Chrome sets a limit on the resources an ad can use. If an ad doesn't comply, Chrome removes the ad from view and replaces it with a removal notice.
When the intervention is triggered, you should see the content in the iframe for a heavy ad replaced with an Ad removed message. If you follow the included Details link, you will see a message explaining: "This ad uses too many resources for your device, so Chrome removed it."
You can see the intervention applied to sample content on heavy-ads.glitch.me You can also use this test site to load an arbitrary URL as a quick way of testing your own content.
Be aware when testing that there are a number of reasons that may prevent an intervention being applied.
Reloading the same ad within the same page will exempt that combination from the intervention. Clearing your browsing history and opening the page in a new tag can help here.
Ensure the page remains in focus - backgrounding the page (switching to another window) will pause task queues for the page, and so will not trigger the CPU intervention.
Ensure you do not tap or click ad content while testing - the intervention will not be applied to content that receives any user interaction.
For more information, visit https://developer.chrome.com/blog/heavy-ad-interventions/