Will it post?
Last updated October 28, 2026
A free checker for social media videos. Pick one and see, network by network, whether it will post as it is: length, aspect ratio, resolution and file size against what Facebook, Instagram, YouTube, TikTok, X, LinkedIn, Pinterest and Threads publish. Where it won't, it says what's wrong.
Your video stays on your device. The page reads it in your browser and never uploads it.
Or drop one anywhere on this page. It stays on your device: nothing is uploaded.
How this works
The page reads the file's header on your device: how long the video is, and how many pixels wide and tall it is when it plays. MP4 and MOV files, which is what phones save, are read directly, whatever the codec; anything else goes to your browser's own video player. The file size comes from your device. Nothing is uploaded, and nothing about the file is sent anywhere. Once the page has loaded, it works with your phone in airplane mode.
Those numbers are checked against the limits each network publishes for videos posted by scheduling apps such as Postango (through its API), rather than from the network's own app. Lengths come from the table of limits Postango uses when it schedules posts, last checked October 8, 2026; aspect ratio, resolution and file size from each network's developer documentation, read October 3, 2026. The social media video limits page has the full table, with a link to every source.
Three things it doesn't check. The video's format (its codec) and frame rate: an MP4 in the common H.264 video and AAC sound format is accepted by every network it checks. Your account: X Premium, a verified YouTube channel or a TikTok account allowed longer videos changes some answers, and the line under each network says when. And what the app on your phone will do: apps can convert a video as they upload it, so they can be more forgiving than this.
File sizes are in megabytes of 1,000,000 bytes, the way phones and Macs count. Windows counts 1,048,576 bytes to the megabyte, so it shows a smaller number for the same file. No network says which it means, so a file between the two readings gets a “Can't tell”.
Not checked: Bluesky, whose API limits aren't in our table yet. Bluesky itself now takes videos up to 10 minutes and 300 MB.
The limits it checks
Captions, hashtags, the notes behind each number and every source are on the full video limits table. For the app's own rules next to the API's, network by network, see the Instagram, TikTok, YouTube Shorts, Facebook Reels and LinkedIn size guides.
- Length: 3 s to 4:00:00. File size: not published. Aspect ratio: 9:16 or 16:9.
- Length: 3 s to 15:00. File size: up to 300 MB. Aspect ratio: 0.01:1 to 10:1, at most 1,920 px wide.
- YouTube
- Length: 15 minutes, or 12 hours from a verified channel. File size: up to 256 GB.
- TikTok
- Length: up to 3:00 on every account, 5:00 or 10:00 on some. File size: up to 4 GB. Aspect ratio: 360 to 4,096 px a side.
- X
- Length: 0.5 s to 20:00 without Premium, 2:05:00 with it. File size: up to 8 GB (16 GB per X's developer docs for Premium accounts). Aspect ratio: 1:3 to 3:1, at most 1280 × 1024 (the same page says Premium accounts can upload 1080p).
- Length: 3 s to 30:00. File size: 75 KB to 500 MB (LinkedIn's Videos API page says 500 MB in one place and 5 GB in another).
- Length: 4 s to 5:00. File size: not published. Aspect ratio: 9:16, 1:2, 2:3, 3:4, 4:5 or 1:1.
- Threads
- Length: up to 5:00. File size: up to 1 GB. Aspect ratio: 0.01:1 to 10:1, at most 1,920 px wide.
Questions
Does Postango keep my video?+
It never gets it. The page reads the video's length and size in pixels from the file's header, on your device; nothing about the file is sent anywhere, not the video, its name or its size. Load the page, switch your phone to airplane mode, and the checker still works.
Why does it say "can't tell" for X on a video over 20:00?+
Because X's limit depends on the account. X's developer docs give a post 20 minutes of video and 8 GB on an account without Premium, and 125 minutes and 16 GB on a Premium account. The checker can't see your account, so between the two it says so. Postango splits a video for X at 20 minutes, the limit every account has: on a Premium account the cost is a video split into parts it didn't need; the other way round, it would be a post that fails.
Does it work with HEVC, HDR and 4K videos?+
Yes, from an iPhone or an Android phone, in any browser. Phones save MP4 or MOV files, and the checker reads their length and size in pixels straight from the file, whatever the codec: H.264, HEVC (H.265), HDR or ProRes. Other kinds of file, such as WebM, go to your browser's own video player; if it can't play one, the checker still checks the file size and says what it couldn't read. Saving a copy as MP4 from any video app fixes that.
My phone posts 4K video to Instagram. Why does this say it won't?+
The checker answers for videos posted through Instagram's API, which is how scheduling apps post, and Meta's developer docs limit those to 1,920 pixels wide and 300 MB. A 4K video is wider than that whichever way up it is. The app on your phone can convert a video before it uploads it; a scheduling app has to send a file that is already inside the limits.
What does “Can't tell” mean?+
That a plain yes or no would be a guess, and the line under the network says why. Usually the network's own documents disagree: LinkedIn's Videos API page gives 500 MB in one place and 5 GB in another, and X's developer docs say a video must be at most 1280 × 1024 pixels, though the same page says Premium accounts can upload 1080p. Facebook and Pinterest list the aspect ratios that work without saying whether others fail. Some limits depend on the account: every TikTok account can post up to 3:00, and only some can post longer; X gives Premium accounts longer videos and bigger files. And a file can land between the two meanings of a megabyte, which no network spells out.