Display Advertising in Google: Formats, Audiences and Measurement

Display advertising is ads with images, animation or video that appear on websites and in apps while people are reading or watching something else. In Google you buy them as Display campaigns in Google Ads and they appear on the Google Display Network (GDN). That is the network of websites and apps where Google can show your ads.

This guide covers how to choose formats and audiences and how to bid and measure so that you can set up a Display campaign yourself.

What display advertising is and where the ads appear

A display ad can be an image you have made yourself or a responsive display ad that Google builds from your headlines, images and logos. The ad appears in an ad space on a publisher's site. The publisher is whoever owns the website or app. According to Google, Display campaigns can also appear on YouTube and Gmail.

Search ads appear when someone is looking for what you sell. Display ads reach people earlier in the buying journey and can remind those who have already visited your website. That is why display is judged on different metrics from search.

How many people the Google Display Network reaches

According to Google, Display campaigns reach more than 35 million websites and apps as well as YouTube and Gmail. Google also states that the network reaches over 90% of internet users worldwide and cites Comscore as the source. How many people you reach in your own market depends on the locations and audiences you choose.

How it differs from other programmatic buying

Programmatic buying means that ad space is bought automatically in auctions. What mainly sets the GDN apart from other platforms is that everything happens in the same Google Ads account as your Search campaigns with the same conversion tracking and the same bid strategies.

If you have linked Google Analytics 4 to Google Ads, audiences you build in GA4 can be used in your Display campaigns. In GA4 you can also track traffic from AI services and other traffic that your display ads influence.

You can see where your ads have appeared in the Where ads showed report. Google points out that the report is not complete and that placements with few impressions may be missing.

What Google's network gives you

• Audiences from Google: Google builds audience segments from how people use Google's services and other websites.
• Remarketing: You can show ads to people who have already visited your website or used your app.
• Several formats: You can upload your own image ads or let Google build responsive display ads from your images and text.
• Cost control: You choose the bid strategy and budget and can control where your ads appear. Whether display is profitable for you is something your measurement will show.

Sizes and types of display ads

Uploaded image ads

An image ad is a finished image or animation in a fixed size. According to Google's specifications the file must be GIF, JPG or PNG and no larger than 150 KB. Here are some of the sizes in Google's list with Google's names for them:

Size in pixels	Google's name
300 × 250	Inline rectangle
336 × 280	Large rectangle
250 × 250	Square
200 × 200	Small square
728 × 90	Leaderboard
970 × 90	Large leaderboard
468 × 60	Banner
120 × 600	Skyscraper
160 × 600	Wide skyscraper
300 × 600	Half-page ad
320 × 100	Large mobile banner
320 × 50	Mobile banner

An uploaded ad only appears in ad spaces of the same size. Google therefore recommends that you also have responsive display ads for the spaces where your own ads do not fit.

Responsive display ads

Responsive display ads are the default format in Display campaigns. You upload headlines, descriptions, images and logos and Google combines them into ads that fit the ad space. Over time the asset report shows you which images and text work best.

Dynamic remarketing

Dynamic remarketing shows previous visitors the products or services they looked at on your website. The products come from a feed that retailers upload to Google Merchant Center. Your website also needs Google's dynamic remarketing tag so that visitors are linked to the products they have viewed.

HTML5 and interactive ads

HTML5 ads can be animated and interactive and can for example include an image gallery that the visitor swipes through. They take more work to produce and according to Google your account must meet three requirements before you can apply to use them:

• The account has been open for more than 90 days.
• The account has spent more than USD 9,000 in total.
• The account has a good history of policy compliance.

Audiences in Display campaigns

My view is that your choice of audience affects results more than anything else in a Display campaign. Google calls audiences audience segments and these are the types available in Display campaigns.

Remarketing with your own data

My experience is that remarketing usually performs best in display and should therefore come first. You show ads to people who have visited your website or specific service and product pages or who have used your app. Google calls these lists your data segments.

You reach existing customers with Customer Match. This means uploading a customer list with email addresses, for example. According to Google's policy you need 90 days of history and more than USD 50,000 in total spend to target ads to the list. Other accounts can use it to monitor and exclude customers.

In-market segments

In-market segments are people who according to Google are researching products and considering buying something in a particular category.

Affinity segments

Affinity segments reach people based on their habits and long-term interests. Examples are sports fans and outdoor enthusiasts.

Life events

Life events reach people around important milestones such as graduating, moving home or getting married. According to Google these segments are often larger than in-market segments because a life event tends to lead to several purchasing decisions.

Demographics and detailed demographics

Demographics in Google Ads are age, gender and parental status. Household income is also available but according to Google only in about twenty countries and Sweden is not one of them. Detailed demographics are broader groups with shared traits. They include:

• parents by age of their children (0-1, 1-3, 4-5, 6-12 and 13-17 years)
• marital status (single, in a relationship or married)
• education (high school graduate, bachelor's degree or advanced degree)
• homeownership status (homeowners or renters)

Placements

With placements you choose yourself which websites, apps or YouTube channels your ads appear on. In my view this is where there is most to gain if you want to control relevance and brand safety. How to put that list together is explained in the guide on how to create your own publisher list.

Combined segments

With combined segments your ad is only shown to people who are in several segments at once. Google's example is outdoor enthusiasts who are also looking to buy a car.

Custom segments

You build custom segments yourself from keywords, URLs and apps. If you enter competitors' websites, for example, Google looks for people with similar interests. Custom segments replace custom intent and custom affinity audiences, which Google merged in 2020.

Similar audiences were removed from all campaigns in August 2023. Google suggests optimized targeting instead.

Optimized targeting

Optimized targeting is switched on by default in Display campaigns. It uses your segments as a starting point and can show your ads to other people if Google finds traffic that converts better. If you only want to reach the segments you have chosen, turn it off in the ad group settings.

The order in which to prioritise your audiences

My recommendation is to prioritise by how close to a purchase people are likely to be:

1. Remarketing to visitors who were close to converting
2. Customer Match with your customer lists
3. In-market segments
4. Custom segments
5. Life events and detailed demographics
6. Affinity segments and broader demographics

Display as support for other channels

Display is often used to support other channels. When display builds awareness before your Google Ads search ads pick people up, it can lead to more conversions in both paid and organic search. Display can also:

• repeat the message from your newsletters
• extend the reach of campaigns on social media
• keep your brand top of mind with the companies your sales team is working on

Display for online retailers

For online retailers display can complement Performance Max and Google Shopping. Performance Max already shows ads on the Display Network. A separate Display campaign is therefore likely to be most useful when you want to control the audience and message yourself.

• Remarketing: Show the products a visitor has looked at with dynamic remarketing and add image ads with lifestyle images that build the brand.
• Upselling: Build segments of existing customers based on what they have bought and show upgrades or products that go with their purchase.

Display ads that get noticed and understood

Why the ad matters so much

A good audience and the right bid will not help if the ad is weak. A display ad is seen in passing and needs to get its point across in a second or so. This usually works:

• a clear headline that says what you offer
• a call to action such as See the models or Book a time so that the next step is clear
• high-quality images that reinforce the message
• an offer that is relevant to that particular audience

Ads on mobile

Your ads need to work just as well on a small screen. Responsive display ads adapt to the ad space. Keep the text short and make sure the button is easy to tap with a thumb.

Bid strategies and optimisation

Which bid strategies are available

Which bid strategy you choose depends on your goal. According to Google these are available for Display campaigns:

• Conversions: Maximize conversions, Target CPA or Target ROAS (target return on ad spend). Google usually suggests one of these when you create the campaign.
• Clicks: Maximize clicks or Manual CPC where you set the maximum price per click yourself.
• Impressions: Viewable CPM (vCPM). You bid per thousand impressions but only pay for those that were viewable. A display ad counts as viewable when at least half of it has been on screen for at least one second.

My recommendation is viewable CPM when the goal is awareness and a conversion-based strategy when you have conversion tracking that works. How the strategies differ is covered in the guide to bid strategies in Google Ads.

Target CPA and paying for conversions

Target CPA sets bids to get you as many conversions as possible at an average cost per conversion (CPA) that you decide. According to Google the strategy can be used even without conversion history and results should be evaluated over 30 days with at least 30 conversions.

With Target CPA you can also pay per conversion instead of per click. According to Google this requires more than 100 conversions in the last 30 days and for 90% of them to happen within seven days of the click.

Review where your ads appear

Go through the Where ads showed report under Insights and reports regularly. Exclude placements that do not deliver results or do not suit your brand. At the same time Google warns against over-optimising because each placement often has few impressions and too many exclusions limit the available ad inventory.

Placements that perform well can get their own campaign with their own message. With topics and display keywords you can also steer towards content about what you sell.

What click-through rate to expect

Click-through rate (CTR) is the share of impressions that lead to a click. According to Google it is often lower on the Display Network than in search because it is harder to catch the attention of someone reading something else. According to Google a low CTR on display does not affect the Quality Score of your search ads.

Google does not publish benchmarks and CTR varies by industry, format and audience. Compare with your own campaigns over time instead. The lower click-through rate has three explanations:

• Context: A search ad is shown to someone who is looking. A display ad is shown to someone who is doing something else.
• Banner blindness: Many people have got used to banners and look past them.
• Influence without clicks: Some people see the ad and convert later without having clicked.

So how do you know whether display is working? Look at view-through conversions and at whether searches for your brand and direct traffic increase. Also follow how the conversion rate in other channels is affected and the total return on ad spend (ROAS) or MER across all channels.

Measurement and analysis

Goals and KPIs

Decide before launch whether the campaign should deliver awareness, leads or sales. The goal determines both the bid strategy and which KPIs you track.

Give the campaign time before you draw conclusions. According to Google the learning period usually lasts 5 to 7 days and after a significant change you should wait 7 to 14 days before assessing performance.

View-through conversions

View-through conversions come from people who saw your ad without clicking and then converted. They capture part of the influence that clicks miss.

According to Google they are used for reporting only in Display campaigns. They appear in the View-through conversions and All conversions columns but not in the Conversions column that bid strategies optimise towards. Google also cannot report them from browsers that block cross-site cookies. The figure therefore probably shows only part of the influence.

Marketing Efficiency Ratio (MER)

MER is total revenue divided by total marketing costs. The metric does not exist in Google Ads and you calculate it yourself.

For display MER is useful because it also captures indirect effects such as more people searching for your brand. It gives a broader picture than click-through rate or cost per click (CPC).