YouTube Shorts, Reels and TikTok: the specs that actually differ
All three platforms take vertical 9:16 video at 1080 by 1920 in MP4, so one master file publishes to all three. The real differences are length ceilings, currently three minutes on Shorts and Reels against sixty minutes for TikTok web uploads, and where each platform's interface covers your frame. Safe zones matter more than any other spec.
What are the current specs for each platform?
| YouTube Shorts | Instagram Reels | TikTok | |
|---|---|---|---|
| Aspect ratio | 9:16 | 9:16 | 9:16 |
| Resolution | 1080 × 1920 | 1080 × 1920 | 1080 × 1920 |
| Maximum length | 3 minutes | 3 minutes | 60 min (web) / 10 min (in-app) |
| Formats | MP4, MOV | MP4, MOV | MP4, MOV |
| Codec | H.264 | H.264 | H.264 |
| Practical sweet spot | 20 - 45 sec | 15 - 40 sec | 20 - 60 sec |
The specs converged years ago and the convergence is the point: a single 1080 by 1920 H.264 MP4 is a valid upload on all three. Anyone re-encoding per platform is doing work the platforms stopped requiring.
It is worth pausing on how favourable that convergence is. The three largest short-form audiences on the internet all accept the same file, which means the distribution problem that would have needed a team and a budget a decade ago is now a matter of connecting three accounts once and never thinking about it again.
The sweet spot row is doing more work than the maximum row. Ceilings tell you what is permitted; they say nothing about what gets distributed. On all three platforms, completion rate is a dominant ranking input, and a forty-second video that holds to the end outperforms a two-minute video that loses people at thirty seconds. The ceiling is a trap for exactly this reason, and it rose because the platforms want longer sessions, not because longer videos perform better for you.
Where does each platform cover your frame?
This is the spec that actually costs people views, and it is missing from most comparison pages. Each platform lays its own interface over your video, and anything underneath is effectively not there.
TikTok is the most aggressive. Roughly the top 15 percent carries the tab overlay, the bottom 20 percent carries the caption and account metadata, and the right 15 percent carries the interaction buttons. Instagram and YouTube are less severe but occupy similar regions.
The most common casualty is burned-in subtitles placed at the traditional lower third. On TikTok that lands squarely under the caption block. Vertical video wants subtitles noticeably higher than film convention suggests, closer to the centre of the frame than the bottom.
Subtitle placement and timing is its own subject, and it decides more of your retention than the visuals do: how to position and time subtitles for muted viewing
What genuinely has to change between platforms?
Very little in the file, and rather more around it. Three things are worth adjusting per destination, and the rest is superstition.
- The text metadata. YouTube runs on search as well as feed, so a descriptive, keyword-bearing title earns discovery there that it does not earn on TikTok. TikTok captions are short and conversational. Instagram sits between the two and cares about hashtags more than either.
- The first two seconds. TikTok's feed is the least forgiving and Shorts is the most, because Shorts pulls from a subscriber base as well as a cold feed. If you are cutting one version for all three, cut it for TikTok.
- Whether you post at all. Not every series suits every platform. Cross-posting is nearly free once the render exists, so the default should be all three, but a subject with no audience on a platform will not develop one through presence alone.
What does not need to change is the render. Because the three destinations take the same file, a series can publish to all of them from one generation pass. AutoVidGen does exactly this: one master goes to whichever platforms you connected, with per-platform titles and descriptions generated alongside it, and no second render.
The cross-posting mechanics, including what each platform's API does and does not allow: publishing one series to TikTok, Reels and Shorts together
Does cross-posting hurt reach?
The widely-repeated claim is that platforms suppress content carrying a competitor's watermark. That part is true and well evidenced, particularly on Instagram and YouTube regarding TikTok watermarks.
The claim it gets confused with is that cross-posting the same content is itself penalised. That is not established, and the evidence usually cited for it is watermark suppression being misread. A clean file with no watermark, published natively to each platform through its own API, is treated as native content, because it is.
The practical rule follows directly: never download from one platform to upload to another. Publish the original render to each destination separately. This is what an API-based publishing pipeline does by default and what manual cross-posting usually gets wrong, because downloading from TikTok is the easy path and it stamps the file on the way out.
Common questions
Can I upload a 16:9 video as a Short?
It will be accepted and it will be letterboxed, which reads as recycled content and performs accordingly. YouTube classifies uploads as Shorts by aspect ratio and duration, so a landscape file under three minutes may not enter the Shorts feed at all. If the destination is vertical, render vertical.
Does a longer Short earn more now that the ceiling is three minutes?
Not reliably. The ceiling rose but the ranking inputs did not change, and completion rate still dominates. Longer videos have more opportunity to lose the viewer, and a partial view is a weaker signal than a full one. Use the extra length when the subject needs it, not because it is available.
What frame rate should I use?
30fps is correct for this kind of content and is what all three platforms deliver to most viewers anyway. 60fps is worth it only for genuine high-motion footage, which narration-over-visuals is not. Higher frame rates cost file size and encoding time for no perceptible gain here.
Should the same video go out to all three at the same time?
Simultaneous publishing is fine and is what most automated pipelines do. There is no cross-platform timing penalty. If you want to stagger, do it because your audiences are in different time zones, not because you believe the platforms are watching each other. They are not.
What in this guide has a shelf life
Checked on 11 August 2026. These are the claims most likely to have moved since, and the ones to verify before acting on them.
- · Every length ceiling in the table - all three moved during 2025 and Shorts moved twice.
- · Safe zone percentages - these track UI redesigns and are the fastest-moving numbers on this page.