What does 'viewability' mean – and why does it matter in digital advertising?

You may have heard the term viewability being used when digital advertising is discussed. But what does it actually mean? And why does it matter – both for advertisers and media?
Here is a simple introduction to what viewability is, how it is measured, and how it can be used strategically.

What is viewability?

Viewability is about whether an ad has actually been visible to the user. It is not enough for an ad to have been "served" in a purely technical sense – it must also have been visible on the screen to count as viewable.
That is why a common standard was introduced by the industry body IAB:

• A display ad counts as viewed if at least 50% of the ad is visible for at least 1 second.
• A video ad must be at least 50% visible for 2 seconds.
• For very large ad formats (like 970x250) the threshold is lower – here only 30% needs to be visible for 1 second.

The purpose? To ensure that advertisers only pay for ads that genuinely have a chance of being seen by humans – and are not just hiding at the bottom of a page.

How is viewability measured?

It sounds simple, but it requires technology behind the scenes. Viewability is measured via small scripts that register:

• Where on the page the ad is placed (e.g. whether it is at the top, middle or bottom).
• How much of the ad is visible on the screen.
• How long it is visible.

Systems like Google Ad Manager have built-in measurement (called Active View), and there are also specialized solutions from providers such as IAS, DoubleVerify and Adnami.

What is viewability used for?

Viewability has become an important metric – both for advertisers and media. Here is why:
For advertisers:

• You want your ads to be seen – not just served.
• Viewability is a good indicator of how effectively a campaign is exposed.

For publishers:

• High viewability means your ad placements are attractive – and can therefore be sold at higher prices.
• Viewability affects the price you get per ad impression (eCPM).

Finding the balance: How high should viewability be?

You might think 100% viewability would be the optimal goal – but in practice that is not always the case.
At STEP Network we often see that the best balance point is around 60% viewability. That is where you get a good combination of visibility and volume.

• Too low (30-40%): Buyers often deselect formats with too little visibility.
• Too high (80-90%): Fewer ads get shown, which can lower overall revenue.

How can you optimize for viewability?

There are several techniques you can use:

• Lazy loading: Ads are only loaded when they are close to entering the user's field of view.
• Placement: Make sure ads are placed strategically – but not necessarily always at the top.
• Refresh logic: Adjust how often an ad is refreshed so it does not hurt visibility.

It is about creating a good experience for the user – while maximizing the value of every impression.

Viewability is not the whole story

Even if an ad is visible, it does not necessarily mean the user noticed it. That is why attention is increasingly discussed as the next step.
Attention measurement looks at how long the ad is in focus, whether the user interacts with it, or whether the user, for instance, stops scrolling while the ad is visible.
There is not yet a common standard for attention, as there is for viewability – but several players in the industry (like Adnami in the Nordics) are working to make it more measurable and actionable.

Summary

Viewability is an important piece in ensuring transparency and quality in digital advertising. It is about making sure ads are seen – not just served. And when used strategically, it can help create better campaigns, higher revenue and a better user experience.
Want to know more about how we work with viewability and attention at STEP Network? Then do reach out.