The short answer
Every guide to this is either out of date or written by someone who has never had a post fail at 6am. This table is the set of limits our own scheduler checks before it queues anything — so it is maintained because we depend on it, not because it makes a nice blog post.
The table
| Platform | Format | Aspect ratio | Max length |
|---|---|---|---|
| Reel | 9:16 | Up to 15 minutes | |
| Story | 9:16 | 60 seconds | |
| Feed post | 1:1 / 4:5 | Up to 60 minutes | |
| TikTok | Video | 9:16 | Up to 10 minutes |
| YouTube | Short | 9:16 | Up to 3 minutes |
| YouTube | Video | 16:9 / 4:3 | Up to 12 hours |
| Reel | 9:16 | Up to 15 minutes | |
| Story | 9:16 | 60 seconds | |
| Feed post | 1:1 / 16:9 | Up to 4 hours | |
| X | Post | 1:1 / 16:9 / 9:16 | Up to 2:20 (longer with Premium) |
| Post | 1:1 / 9:16 / 16:9 | Up to 10 minutes | |
| Pin | 2:3 / 9:16 | Up to 15 minutes | |
| Threads | Post | 1:1 / 9:16 | Up to 5 minutes |
What actually gets a post rejected
In practice, uploads fail for three reasons, and only one of them is fatal.
- The clip is too long for the format. This is a hard rejection. A 3-minute video is fine as a Reel and impossible as an Instagram Story.
- The file is too large. Our own ceiling is 500 MB per file; platforms vary, and a long 4K export hits this faster than people expect.
- The aspect ratio is wrong. This usually is *not* a rejection — the platform crops or pillarboxes it. Which is worse, because it publishes and simply performs badly.
Which aspect ratio to shoot
If you are producing one video for several destinations, shoot 9:16 vertical. It is native on Reels, TikTok, Shorts, Stories and Threads, and it is accepted on X, LinkedIn and Pinterest. The only place it is genuinely wrong is a long-form YouTube upload, which wants 16:9.
The reverse does not hold. A 16:9 clip pushed to Reels gets letterboxed into a small strip in the middle of a phone screen, and that is the single most common reason a repurposed video underperforms.
Checking this automatically
Keeping a table like this in your head does not scale past about two platforms. Most schedulers treat a video as a file to upload; ours checks it against these rules before the post is queued — a clip over the length cap is a blocking error, and a mismatched aspect ratio is a warning you can override.
That check is available on the free plan, which covers 5 channels with no cap on how many posts you schedule. If you are comparing options, we put every free tier side by side in free social media schedulers, compared.
Common questions
What aspect ratio works on all social media?
9:16 vertical is accepted everywhere and is native on Instagram Reels and Stories, TikTok, YouTube Shorts, Facebook Reels and Threads. The exception is long-form YouTube, which expects 16:9.
What is the maximum video length for Instagram Reels?
Up to 15 minutes as of August 2026. Instagram Stories are capped much lower at 60 seconds per segment, which is the limit people hit unexpectedly when repurposing a Reel.
Why did my video upload fail?
Almost always length or file size. Length caps vary sharply by format — a clip that is fine as a Reel can be too long for a Story on the same platform. Aspect-ratio mismatches usually do not block the upload; they get cropped instead.
Can I post the same video to Instagram, TikTok and YouTube?
Yes, if it is vertical and under 3 minutes — that clears YouTube Shorts, which is the tightest of the three. Above 3 minutes it still works as a Reel and a TikTok but becomes a regular YouTube video rather than a Short.