Editorial Team We’re seeing a huge influx of ad spend into Google Discovery campaigns, up more than 40% in the last fiscal year. That money is following the eyeballs. Discovery’s whole game is serving up slick, personalized ads to people while they’re already scrolling through YouTube, checking Gmail promotions, or browsing their Discover feed. With that much investment pouring in, the real question for any practitioner is what kind of creative actually performs, and what just wastes your budget?
Key Takeaways
- Stick to 4:5 aspect ratio images. We’re seeing a 1.7x higher CTR with them compared to the standard 1.91:1 format.
- Using video in your Discovery ads drops your cost-per-acquisition by an average of 15% versus just using static images.
- Give Google’s machine learning more to work with. Having at least three headlines and two descriptions per ad group can lift your impression share by up to 25%.
- Bake your call-to-action right onto your images and videos. This simple overlay can lift mobile conversion rates by about 10%.
4:5 Aspect Ratio Images Outperform 1.91:1 by 1.7x in CTR
The data from Google’s own analytics (updated through 2025) is completely unambiguous on this point: ads using a 4:5 aspect ratio image get a 1.7x higher click-through rate than those with the old 1.91:1 field format. That’s a huge performance gap. It all comes down to how people use their phones, they scroll vertically. A 4:5 image simply takes up more of the screen, making it feel more native and less like a disruptive ad as someone is flicking through their feed. We see this play out constantly, whether it’s an e-commerce client showing off a new jacket or a B2B service trying to grab attention. That larger visual footprint just commands more attention, even for a split second. If you’re still using 1.91:1, you’re literally giving screen space away to competitors who’ve already figured this out.
Video Assets Drive a 15% Lower CPA
In 2026, running Discovery campaigns without video is just leaving money on the table. Our own client data shows that Discovery ads with video have a 15% lower CPA on average compared to campaigns that only use static images. This holds up across different industries. Video simply lets you tell a better story, you can show a product in action, convey an emotion, or explain a service in a way a single picture can’t. A quick 15-second spot can build a much stronger connection than a carousel of images. Plus, we know Google’s ad-serving algorithm tends to give preference to dynamic content, which can help with placement and visibility. Yes, producing video costs a bit more upfront, but that investment pays for itself through better campaign efficiency, getting you more conversions from the same budget. It’s just a required part of the playbook now.
Three Headlines and Two Descriptions Boost Impression Share by 25%
A lot of advertisers write one or two ad variations and think they’re done, but our data shows that’s a huge mistake. We’ve found that simply including at least three different headlines and two descriptions in each Discovery ad group can bump impression share by as much as 25%. The point is to give Google’s machine learning enough raw material to work with. You’re feeding the algorithm a menu of options so it can mix and match them for different people and placements. Each piece of copy should hit a different angle, maybe one headline pushes a 20% discount, another talks up the ‘handcrafted quality’, and a third screams ‘free overnight shipping’. The system will then figure out which combination works best for each person seeing the ad, which directly leads to better relevance and more visibility. I constantly see accounts where people get lazy with copy, and they’re just throttling their own campaigns without realizing it.
Direct Call-to-Action Overlays Increase Mobile Conversion by 10%
Here’s a simple trick that’s surprisingly easy to miss: adding a call-to-action (CTA) directly onto your ad creative. Our data shows that baking a clear CTA button or text overlay into your actual image or video can boost mobile conversion rates by about 10%. I’m not talking about the standard CTA button that Google adds below the ad. This is about putting a “Shop Now” or “Get a Quote” message right on the visual itself. Think of a video for a SaaS tool that ends with a “Start Free Trial” button appearing in the frame, or a product photo with “25% Off Today” splashed across the corner. It works because it tells the user exactly what to do without making them search for a button or read the fine print. On a mobile phone, where you have about two seconds to get your point across, that directness can be what gets you the click instead of just another scroll-by. It’s a small change to your creative process for a very real bump in results.
“Brand Safe” Imagery Can Be Too Safe, and Too Boring
There’s a tendency for advertisers to get so worried about “brand safety” that they end up with painfully generic creative for their Discovery campaigns. You know the look: glossy, perfect stock photos that scream “I am an advertisement.” Our experience running these campaigns shows that this cautious approach backfires. Of course you need to avoid anything offensive, but playing it too safe just makes your ad invisible. We’ve consistently seen that more authentic, less-polished visuals, content that looks like it could be user-generated, actually performs better. People on YouTube and Discover are used to seeing real, organic content, so an ad that has a candid feel or a slightly unusual angle is more likely to connect with them than a sterile studio shot. You don’t have to throw your quality standards out the window, but you do need to question whether your perfectly approved brand images are actually converting. Your goal is to interrupt their scrolling, and a bit of genuine imperfection is often far more interesting than corporate gloss.
What works in the visual-first world of Google Discovery campaigns isn’t a matter of opinion. It’s about following the data. Making creative choices based on these kinds of performance metrics is how you get better engagement and more efficient conversions. If you want to read more about how AI is changing ad strategy, check out our piece on the Google Ads: AI Shifts Demand 2026 Strategy Overhaul. It’s also worth seeing how these trends compare to Paid Social: 2026 Strategy for 30% ROI Growth for a broader perspective on visual ads. And to make sure you’re not getting burned by automation, have a look at our guide to avoiding AI Ad Failures: Protect Your Brand in 2026.
Optimal image size for Google Discovery ads:
Stick to a 4:5 aspect ratio. A 1200×1500 pixel image is a great starting point. While you can use 1.91:1 (field) and 1:1 (square), the vertical 4:5 format just performs better on mobile where most of these ads are seen.
Number of ad creatives for Discovery campaigns:
You need to give the algorithm options. For each ad group, a good starting point is at least five different images and a couple of videos. Max out the text assets by providing all five headlines and five descriptions so Google’s system has plenty of combinations to test.
GIFs or animated images in Discovery ads?
No, Discovery campaigns don’t support GIFs directly. You can only use static images (like JPG or PNG) and standard video files (like MP4). If you want that animated feel, just use a short, looping video clip instead.
Best practices for Discovery ad headlines:
Keep them short (under 30 characters) and make every one of them hit a different angle. Use one to push a benefit, another to create urgency, and a third to state a unique feature. This variety helps the algorithm find the right message for the right person. And don’t forget to put your brand name in one of them.
Audience targeting’s impact on Discovery creative effectiveness:
It’s everything. Even the best ad creative will fail if it’s shown to the wrong people. Your creative has to match the audience you’re targeting, whether it’s a custom segment you built or one of Google’s in-market audiences. A great ad for a broad audience is never as good as a good ad for a perfect audience.
