Publisher resources

Increasing ad viewability

Publift Staff, Account Management

4 October 2017

Let's discuss some techniques you can use to improve your viewability scores and increase your site earnings.


In the last blog post we discussed how poor ad viewability might be reducing your site’s advertising earnings. For this blog post we’re going to discuss some techniques you can use to improve your viewability scores and increase your site earnings.

Use the best performing ad sizes and ad positions

The 2 factors that will have the biggest influence on your ads’s viewability rates are the ad sizes you use and where you put them on the page. Firstly – which ad sizes should you use?

Longer/vertical ads + 22% Viewability

When we looked at the performance of all ad sizes across our top 10 publishers we found vertical ad units (like the 300x600 and 160x600 above) averaged viewability rates of 59%. That was 22% higher than other common sizes like 300x250s and 728x90s. We recommend trying to use at least 1 vertical ad unit on every page of your site. Preferably in the sidebar of your site layout to avoid interference with your site content.

Next is ad position. Most pages we manage have 3 common ad positions – a leader at the top of the page, an ad in the sidebar and another leader at the bottom of the page. Subtle changes to exactly where you position these ad units can dramatically affect the viewability of those ads. For example – positioning the top leader below your site navigation bar instead of at the top of the page. When this ad unit is above the navigation bar -  users often scroll down the page before the ad loads. Which means the viewability is poor. When you place this ad unit below the site navigation bar – the content below is visible while the ad unit is loading. On the top sites we manage we saw publishers that moved the top leader ad unit below the site navigation bar had 19% higher viewability for that ad unit than the publishers that left the ad unit above the navigation bar.

970 x 250

In a similar vein – moving the bottom ad unit above the comments, author biography and/or the page navigation bar can dramatically increase ad interaction and viewability. We tried this change on a news site we manage. We also increased the size of the ad unit from 728x90 to 970x250. The CPM of this ad unit increased a whopping 27%

For the sidebar ad unit we’d recommend using a 300x600 instead of a 300x250 and making the ad unit sticky. We’ll cover this in more detail under the ‘make sidebar ads sticky’ section below.

For mobile pages – the top mobile leaderboard (320x50 and/or 320x100) underperforms on all sites we’ve assessed. As mobile connections are usually slower than desktop ones – the problem of the user scrolling down before the top ad unit loads is even more exaggerated. We found that using a 300x250 ad further down the page (ideally with part of the ad poking above the page fold) drove a much higher ad viewability on mobile and average eCPM increased 68%.

Make sidebar ad units sticky

Sticky ads follow users as they scroll down the page. When used correctly they can significantly improve the performance and appearance of ads. Make sure they do not cover or hover over other content though. They should only be sticky where there is no content below them.

Most site layouts have the main content body section on the left and a narrower sidebar on the right. If you really want your ads to be interacted with and drive strong eCPMs – you can of course put them in amongst the content section on the left. The reality is, that most premium looking sites we work with will not position an ad over there though. It’s just too intrusive and annoys too many users. If you feel this way – you have to put some kind of ad unit in the sidebar of the page. These sidebar ad units often have poor viewability because the user scrolls down through the content on the left without seeing or interacting with the ad unit on the right. A good way to increase interaction and viewability for this ad unit is to make it longer and sticky. Here’s an example of the change we made on one of our publisher’s homepage:

This sidebar ad unit used to be a 300x250 and it sat below social buttons on the right. By switching this ad unit to a 300x600 and making it sticky – we achieved a 3% increase in viewability and a 37% increase in eCPM.

Lazy load ad units with poor viewability

Lazy loading allows to you to delay loading parts of the page that are out of view, until the user scrolls down. As well as improving site speed, lazy loading often increases ad viewability. Only ad units that are seen are loaded. We recommend lazy loading below the fold ad units which have poor viewability. These ad units often load without the user ever reaching that part of the page and they are the ad units advertisers are trying to exclude from their campaigns. They provide no value to the advertiser as the user never sees the ad. By lazy loading these ad units you can increase account average viewability score.

This is the impact on viewability of lazy loading BTF ad units on one of our real estate publishers. Viewability went from around 35% to nearly 60% while eCPM for those ad units jumped 80%. We don’t recommend using lazy loading on all ad units though - it can cut sellable impressions significantly. We recommend only using lazy loading on BTF ad units with low viewability to drive your account average viewability.

Test a few of those suggestions out and see if your earnings start to increase

If your ad revenue has been affected by poor ad viewability – making these changes won’t reverse that impact overnight. On the sites we made these changes we measured 30 days before against 30 days after. We think the bigger impact actually came after this period when advertisers started to recognise site viewability had increased. That’s when you’ll start to see the big CPMs from those top advertisers hitting your site.

If you want to test any of the changes mentioned above but don’t have time or the dev resources – contact us and we’ll see if we can help you increase your ad revenue.



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