We try as many different approaches to monetize our clients websites as they are comfortable with. This doesn’t stop with normal display advertisements, but also includes special formats that draw more attention. The most popular (among advertisers) are pop-ups and pop-unders. The question is often, how users react on those ad formats. Will they leave your site, block or ignore or interact with the ad? I recently tested the bounce rate of a website with a pop-under and discovered even more than I expected.

What are Pop-Unders and Pop-Ups?

Pop-Unders and Pop-Ups are technically almost identical. Both open an ad in a new window or tab (depending on the browsers default behaviour). The pop-op opens the window in front of the current site, so it is visible right away, while the pop-under opens the window “below” the current window so that the users sees it when closing the window.

Why the difference? Imagine you opened a lot of tabs in your browser and when closing some of them there is an extra window with an ad. How would you know from which site the ad comes from? The pop-under window is not less attractive as the pop-up, but in case the user feels disurbed, he might not connect his negative emotion to the website that loaded the ad (= your website).

How much can you earn from Pop-Unders and Pop-Ups?

Why should you – as a publisher – implement a pop-under on your site? Well, the income potential is higher than with normal banner formats. This is also due to the fact, that they are more visible and some more users might click. Since advertisers like to get attention and normal display ads get less and less of it, pop-under and pop-up formats became attractive again.

I have tried pop-formats on many of my own and my clients websites. Since they are from very different countries and with different languages, the performance varies a lot. On a project from the US we recently sold pop-unders for $1.50 on mobile and $4.00 on desktop for traffic from the US, UK and Canada.

Since pop-unders and pop-ups get paid more, there is normally a capping and limitation on specific geo locations. See my two following examples for that.

Mind the capping

On websites with a lot of page views per users, the capping prevents visitors from seeing a pop-under or pop-up ad more than maybe 1-3 times per day. This is not only useful to not stretch your visitors patience too much, but also to prevent advertisers from spending too much on visitors that just don’t want to interact with the ad.

Mind your visitors location

I know that there are a lot of blogs from India with English content, but they don’t really earn a lot from pop-unders if their traffic is mostly from India itself. The best (advertisement) markets for content in English are still the US, Canada, the UK and Australia.

How visitors react on pop-unders and pop-ups?

Just recently, a client wanted to know how pop-unders influence his visitors behaviour and so we setup a test using custom variables in Analytics. We displayed the pop-under to half of the visitors while the other half didn’t see it. The pop-under was loaded on the first two page views. These are the numbers:

 sessionspages views / sessionavg. duration
with pop-under29424,645:32 m
no pop-under27324,865:55 m

These numbers look a lot like people would (almost) not mind the pop-under. One can really argue if the test results are significant enough to make any assumption, but the numbers are at least showing that the reaction on pop-unders is not that horrifying – in this case.

For now, we only have some assumptions about the results. The website we ran the test on is a blog with information for a non-technical group. The information are well written and helpful to the user. The crux of this matter is that over 80% of the visitors are new, coming from search engines. We assume they plan on leaving anyway after they found their information.

AdSense income about 35% higher

Once you did setup a test like we did using Google Analytics custom variables you are able to discover a lot more than the numbers I mentioned here. There is one difference between visitors who saw the pop-unders and those who didn’t that I just catched by accident: the AdSense income is different.

The AdSense income from visitors who didn’t see the pop-under was about 35% higher to the one from visitors seeing the pop-under. Due to the relatively small test group I don’t want to draw early conclusions from this, but the influence of pop-unders on other ads might result in some more tests.

The real problem

The test above ran for over a week. So you might ask yourself why to bother for a website that has so few traffic? The truth is that the site has actually a lot more visitors, but pop-unders and pop-ups don’t get displayed often for different reasons. In the example site from above, the pop-under gets served in only 25% of the sessions. These are the main reasons for that.

  • blocked by ad blockers
  • blocked by browsers
  • manually disabled
  • limitations by ad network

Pop-ups get blocked

Popups and Popunders not only get blocked by ad blockers, but also by most browsers. You might know this small notice on the top telling you that the site tries to open a new window. How would you react as a user here? There is nothing you, as a publisher, can do here as well.

In our use case, only because of ad blockers and the browser behaviour, only 25% of the target group for pop-unders got served. The next reason might decrease this number even more.

Manually disable Pop-Unders

Dispite the good income potential you might also want to disable pop-unders for some browsers manually. In the above case we didn’t, because we wanted to check for the maximum potential. In another project we disabled pop-unders for most mobile visitors, because on a lot of smartphones and tablets the pop-unders worked like a pop-up and sometimes where even hard to close. In the best case your users complain and you have a chance to adjust something. In the worst case users just leave for good.

To decrease user penetration and frustration we also sometimes setup pop-ups and -unders for only every second or third page view and not on the first page view or the home page, so user get at least the chance to like us a bit before the ad pops up.

For the reasons mentioned above, we are loading pop-unders on our own site for less than 10% of the sessions. Even with a good performance of the pop-ads the outcome can question the effort put into pop-under optimisation.

Limitations by the ad network

As mentioned above, pop-formats often have more restrictions regarding the visitors location and language than other ad types. The test site didn’t lack from this problem, but websites with a geographically more diverse target group will suffer from this problem that might cause a serious limitation of income potential.

The other limitation set by the ad vendor is capping. This is mostly in the range of 1-3 pop-ups per visitor per day.

Use case: Sites with returning visitors

I already wrote about our results on a blog with mostly new visitors. So would a site with faithful visitors lack from pop-unders? Yes and no.

In case pop-unders disturb your visitors experience, the more engaged your visitors are, the more of them will complain. Due to user feedback we were able to setup pop-unders in a way that it only displays to visitors who – from a technical point of view – don’t get disturbed too much. When finished, there was no negative feedback coming in while the site is still growing in traffic.

Final Assumptions

  • pop-under and pop-ups generate a higher CPM/income than normal display ads
  • the more important your content is to the user, the more they will accept pop-ads
  • mobile visitors feel more disturbed than desktop visitors
  • most pop unders and pop ups get blocked by either AdBlockers or Browsers
  • observe, how your other income sources develop

The Author


  1. Dhinesh

    thanks for the article. Can you suggest a trustable pop up/under ad company? I am afraid of trying those because i couldn’t choose the right one which pays with reasonable CPM. If you could share your experience with any of the pop ads company and suggest one, it will be highly helpful. Hoping for a reply.

    1. Thomas Maier Article Author

      Hi Dhinesh, I tried and try different and still gather some information for a new post about this, but you might want to take a look at AdCash.

  2. Lana


    We’ve been using pop-unders for a few months, and last month we started seeing drop in viewability. It gradually went from over 90% to about 30%.

    We didnt make any changes and our traffic stats didnt change. The ads are not blocked, but viewability decreased. We suspect that the drop is due to Google opening pops into tabs, but can’t prove or disprove it.

    Did you ever have this kind of issue?

    1. Thomas Maier Article Author

      Sorry, but I haven’t had this issue before so have no idea of what happened.