Meta Creative Specs That Actually Matter (And the Ones That Don't)

I was reviewing a campaign last week with a manufacturer who'd spent three days perfecting their video export settings.

4K resolution. Color grading. Audio mastering. The file was pristine.

It was also 280MB and took seven seconds to load on a 4G connection.

Their CPM was 40% higher than it should've been because Meta's algorithm was penalizing them for slow load times. All that time spent on quality settings that didn't matter, while ignoring the one spec that actually killed performance.

Here's the truth: Meta publishes a long list of technical specifications. Most of it keeps your ad from getting rejected. But only a handful of specs actually impact whether your ad performs.

Knowing the difference saves you time and money.

Vertical Video Isn't About Screen Real Estate

Everyone knows Meta recommends 9:16 vertical video for Stories and Reels. Most people think it's just about filling the screen instead of showing black bars.

That's part of it. But not the main reason.

The real issue is pattern recognition. When someone scrolls vertically through content, a horizontal video breaks the flow. It looks different. And different signals "ad" instead of "content."

Meta's algorithm has learned that horizontal videos get scrolled past faster. So it rewards vertical video with better delivery. HubSpot's research backs this up with hard numbers: vertical video generates 90% more impressions than square or horizontal formats on mobile.

Here's what actually matters: 1080x1920 pixels minimum. Shoot or render in 9:16 from the start. Don't crop a horizontal video and hope it works. The framing will feel off and you'll lose your hook in the conversion.

If you're running the same creative across Feed and Stories, make two versions. One square (1:1) for Feed. One vertical (9:16) for Stories and Reels. Don't try to force a single asset into every placement and expect it to perform everywhere.

Why Auto-Captions Kill Performance

Meta can auto-generate captions for your videos. It's easy. Just check a box and you're done.

It's also costing you money.

Auto-captions are fine for compliance. But they're terrible for performance. You can't control timing, emphasis, or visual hierarchy. The text appears in a generic font, in a fixed position, with zero design consideration.

Hard-coded captions burned directly into the video let you control everything. You can time them to match the visual. Bold key words for emphasis. Use color and motion to guide attention. Position them so they don't cover important product shots or faces.

Research from Verizon Media and Publicis shows that 80% of people are more likely to watch an entire video when captions are available. But the quality of those captions matters. Hard-coded captions that are designed as part of the creative outperform auto-generated ones in both hold rate and completion rate.

What matters: Use large, high-contrast text. White with a black stroke is standard because it's readable on any background. Position captions in the lower-middle third for 9:16 video so they don't cover faces or key shots. Keep each caption on screen for 2 to 3 seconds max. Long enough to read, short enough to keep pace.

The Thumbnail Problem Nobody Talks About

Meta will auto-select a thumbnail from your video. Don't let it.

I've seen this kill campaigns. The algorithm picks a blurry transition frame or a poorly lit mid-moment shot. That's the first thing people see in Feed placements before the video plays. If it doesn't grab them, they never hit play.

Here's the test: pause your video at three seconds. If that frame doesn't make someone want to watch, your thumbnail is wrong.

The best thumbnails have three things. High contrast so they stand out in a busy feed. A clear subject that's immediately identifiable. And visual tension, something unresolved that creates curiosity.

Avoid static product shots. Avoid logos. Avoid anything that looks like stock photography. The thumbnail should feel like a moment frozen mid-action.

What matters: Upload a custom thumbnail as a separate asset. Don't rely on Meta's auto-select. Export it as a 1080x1920 JPG at 85% quality. Keep the file size under 200KB so it loads instantly.

File Size Matters More Than Resolution

Meta accepts video files up to 4GB. Most people export at maximum quality because they assume higher resolution equals better performance.

It doesn't. It just makes your file bigger.

Large files take longer to load, especially on slower connections. And Meta compresses everything anyway. Exporting at 4K doesn't help. You're just increasing upload time and risking slow load speeds for people who see your ad.

Here's what actually matters: Export at 1080p with H.264 compression. Use a bitrate of 5 to 8 Mbps for video and 192 kbps for audio. Keep your final file size under 100MB for videos under 60 seconds.

This balances quality with load speed. If your video looks great on desktop but performs poorly on mobile, file size is usually the problem. Meta's algorithm down-ranks slow-loading content because it creates a bad user experience.

Placement Strategy: When to Split, When to Combine

Meta's Advantage+ placements automatically distribute your ad across Feed, Stories, Reels, and in-stream video. One ad, multiple placements, let the algorithm optimize.

Sounds efficient. In practice, it's a coin flip.

Advantage+ works if your creative is actually optimized for every placement. But most creative isn't. A 9:16 Stories ad looks awkward in Feed. A horizontal in-stream video gets crushed in Reels.

The algorithm will find the placements where your creative works and avoid the ones where it doesn't. But you're leaving performance on the table.

Better approach: separate campaigns by placement and optimize creative for each. Run 9:16 vertical exclusively in Stories and Reels. Run 1:1 square exclusively in Feed. Run 16:9 horizontal exclusively in-stream if you're testing that placement.

Meta's own guidance shows that placement-specific creative outperforms Advantage+ creative by 20 to 40% in engagement metrics. The algorithm is good, but it can't fix creative that's mismatched to the placement.

What matters: If you use Advantage+ placements, test both square and vertical creative variations in the same campaign so the algorithm has options. If you see one placement dominating delivery, that's your signal to split into separate campaigns and optimize further.

The Specs That Actually Drive Performance

Meta's published specs keep your ad from getting rejected. That's the baseline.

The specs that drive performance are different. Vertical 9:16 video signals native content. Hard-coded captions are engagement tools. Custom thumbnails are your first impression. Optimized file sizes impact load speed and algorithm ranking. Placement-specific creative is the difference between good and great.

Learn more about optimizing your ads with our Creative Optimization framework. Build creative to the machine specs, not your own preference sheet.

Because on Meta, just like on the shop floor, the details that seem small are often the ones that determine whether the part runs true or ends up as scrap.

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