If you've built video ads for TikTok or Meta and are now setting up campaigns on Reddit, the first question is simple: will your existing file just work, or does Reddit want something different? This reddit video ad specs guide answers that directly, then walks through aspect ratio, resolution, file format, length, and the small details that cause an upload to get rejected or auto-resized in a way you didn't plan for.
Reddit Video Ad Specs Guide: Aspect Ratio, Resolution, and File Basics
Reddit's ad surfaces are not one single shape. Depending on where your ad shows — the home feed, a subreddit feed, or a full-screen video unit — the platform may expect square, vertical, or landscape video. Before you export anything, decide which placement(s) you're buying, because that decision drives the aspect ratio you should shoot and edit for.
- Square (1:1) is a safe default for standard feed placements across both desktop and mobile.
- Vertical (4:5 or 9:16) fills more of the mobile screen and is worth testing for feed and full-screen video placements, the same way it performs well on TikTok and Reels.
- Landscape (16:9) still shows up in some placements and is useful if you're repurposing a YouTube or website video.
- Resolution should match the aspect ratio at a standard HD or higher pixel count (for example, 1080×1080 for square or 1080×1920 for vertical) rather than stretching a lower-resolution file to fit.
Treat the exact pixel dimensions, maximum duration, and maximum file size as numbers to verify in Reddit's current advertiser help documentation right before you upload. Platforms adjust these limits over time, and uploading against outdated numbers is one of the most common reasons an otherwise good ad gets flagged or compressed in a way that hurts quality.
Placements That Change What You Need
Reddit's ad units aren't interchangeable. A clip built for one placement can look cropped, letterboxed, or oddly centered in another if you didn't plan for it.
- Feed video ads sit between organic posts and typically favor square or vertical framing so the video doesn't shrink to a small strip on mobile.
- Full-screen or immersive video units (where available) behave more like a Stories-style vertical placement and reward a 9:16 edit with a strong first frame.
- Carousel or multi-image units with video need each asset cropped consistently so the sequence doesn't feel jumpy from one card to the next.
- Desktop-first placements can tolerate landscape or square better than vertical, since the surrounding feed layout is wider.
File Format, Length, and Size: What to Confirm Before Upload
MP4 with standard H.264-style compression is the safe starting point for almost every ad platform, Reddit included. If you're exporting from editing software, choose an MP4 preset rather than a MOV or raw export, since container format mismatches are a frequent cause of failed uploads.
On length, shorter cuts are generally easier to fit across placements without additional trimming. A good working approach is to produce a primary cut in the 15–30 second range and keep a slightly longer version only if you specifically need it for a placement that supports longer video. For a broader look at how length expectations shift platform to platform, the guide on product video ad length for different platforms is a useful companion to this one.
On file size, compress before you upload rather than relying on the platform to do it for you. A file that's already optimized (reasonable bitrate, no unnecessary 4K export for a feed ad) uploads faster and keeps more control over how the final video actually looks once it's live.
Reddit Video Ad Specs at a Glance
| Spec | Starting point to use | Why it matters |
|---|---|---|
| Aspect ratio | Square (1:1) as default; test vertical (4:5/9:16) for mobile-heavy campaigns | Matches more of the screen and avoids awkward cropping |
| Resolution | Standard HD or higher, matched to the chosen aspect ratio | Prevents blurry or stretched playback |
| File format | MP4 (H.264-style compression) | Most compatible container for upload and playback |
| Length | 15–30 seconds as a primary cut | Fits more placements without extra trimming |
| File size | Compress before upload; don't rely on auto-compression | Faster uploads and more control over final quality |
| Audio | Design for muted autoplay, add captions | Keeps the message clear with sound off |
Common Reasons Reddit Rejects or Resizes Video Ads
- Uploading a landscape file to a placement designed for square or vertical, which forces an unflattering automatic crop.
- Using a container format other than MP4 and discovering the issue only after an upload fails.
- Shipping a file with no captions, so the message is lost in the first few seconds of muted autoplay.
- Exporting at a bitrate so high the file exceeds size limits, or so low the video looks compressed once it's live.
- Designing the key offer or logo too close to the edge of the frame, where it gets cropped by a different aspect ratio than intended.
A Pre-Upload Checklist for Reddit Video Ads
- Confirm which placement(s) you're buying and match the aspect ratio to that placement.
- Re-check current duration and file size limits on Reddit's own ad specs documentation, since these can change.
- Export as MP4 at a resolution that matches your aspect ratio without unnecessary upscaling.
- Add word-by-word or burned-in captions so the ad works with sound off.
- Keep your logo, offer, and call to action inside a safe center zone so they survive a crop to a different ratio.
- Preview the ad at actual size on a phone screen before you spend budget on it.
How Reddit Specs Compare to Other Feed Platforms
If you're running the same campaign across several networks, it helps to see the pattern: most feed platforms converge on a handful of aspect ratios (square, 4:5, 9:16) and MP4 as the safe file format, but differ on exact size and length ceilings. The Facebook video ad specs and aspect ratio guide, the Instagram feed video ad specs guide, and the Pinterest video ad specs guide are useful references for building one source video that adapts cleanly to each destination rather than re-editing from scratch every time.
How FrameNotion Fits Into a Reddit Video Ad Workflow
Once the specs are sorted, the bigger time cost is usually producing a video in the first place. FrameNotion reads a product or website link and has FrameNotion AI write and render a 30-second vertical ad (1080×1920, 9:16) with a hook, problem, benefit, proof, offer, and call to action built in — along with an AI voiceover, music, and word-by-word captions so it's designed to work with sound off from the start. Every ad also comes with 4:5, 1:1, and 16:9 versions, which makes it straightforward to pick the crop that matches whichever Reddit placement you're targeting instead of re-shooting for each shape.
FrameNotion doesn't publish directly to Reddit or any ad platform, and it doesn't track performance once an ad is live — you'll still upload the file yourself and check results in Reddit's own ads manager. What it does handle is the production bottleneck: a finished ad takes about 10–20 minutes, and text or color changes can be requested afterward without starting over. You can see the format options on the features page, browse finished examples on the examples page, or compare plans on the pricing page before testing it on your next Reddit campaign.
If you've used a poster or flyer for a sale, launch, or event, FrameNotion can also turn that directly into a motion video by animating its existing title, artwork, and badges to music, which is a fast way to get a square or vertical cut ready for a feed placement without designing a new video brief from scratch.
Frequently asked questions
What file format should I use for a Reddit video ad?+
MP4 with standard compression is the safest starting point. It's the most widely compatible container across ad platforms, including Reddit, and avoids the upload issues that can come with MOV or raw camera exports.
Does Reddit prefer square, vertical, or landscape video ads?+
There's no single required shape. Different placements favor different aspect ratios, so match your export to the placement you're buying rather than assuming one ratio works everywhere. Square (1:1) is a reasonable default to test first.
How long should a Reddit video ad be?+
Shorter cuts generally fit more placements without extra trimming. A primary cut in the 15–30 second range is a practical starting point to test, with a longer version only if a specific placement supports it.
Why did my Reddit video ad get cropped after upload?+
This usually happens when the uploaded aspect ratio doesn't match the placement, forcing an automatic crop. Keeping your logo, text, and call to action inside a safe center zone reduces the risk of important elements getting cut off.
Can FrameNotion publish ads directly to Reddit?+
No. FrameNotion creates the finished video file, including 9:16, 4:5, 1:1, and 16:9 versions, but you upload it yourself through Reddit's ads manager. It doesn't publish directly to any platform or report on ad performance.