What this video checker tests, and where its numbers come from
What it checks
For every placement the tool compares four things: duration against the minimum and maximum length, file size against the upload cap, width to height ratio against the allowed range, and pixel dimensions where a minimum is published. A row shows fits only when every check that has an official figure passes. If a rule is a recommendation rather than a limit, such as 9:16 for Reels, the video still fits and the row carries a note instead of a failure.
When a video is too long the tool states the overage and the length to trim to. When it is too large it works out the average bitrate that would land under the cap for your duration, so you can set it in your editor or export dialog. When the shape is wrong it gives the crop that reaches the required ratio from your current frame.
Sources for the limits
X: docs.x.com media best practices. Instagram: the Graph API IG User media reference. Facebook Reels: the Reels Publishing API guide. Threads: the Threads API posts guide. YouTube Shorts: YouTube Help. LinkedIn: the Videos API on Microsoft Learn. Bluesky: the public lexicon for video embeds. Mastodon: the server source code. TikTok: the Content Posting API creator info reference. All were checked in October 2026.
File sizes treat one megabyte as 1,000,000 bytes and one gigabyte as 1,000,000,000 bytes. That is the stricter reading, so a file that passes here will not fail on a smaller definition.
Limitations
Most limits here come from developer documentation, which can differ from what a phone app accepts. The Facebook Reels page still says 90 seconds and may lag the app. The Bluesky duration is approximate because only the size limit is in its public specification. Pinterest and LinkedIn publish no organic length cap we could verify, so those rows check only what is documented. Servers may also re-encode your upload, and a file that fits can still be rejected for its codec. Treat a fits result as a strong sign, not a guarantee.
Frequently asked questions
How long can an Instagram Reel be?
Instagram's publishing API lists Reels from 3 seconds up to 15 minutes, with a 300 MB file cap and any aspect ratio from 0.01:1 to 10:1, with 9:16 recommended. Story videos are 3 to 60 seconds. The app has changed its in-app length more than once, so this tool uses the documented API figures and tells you when a result is only a recommendation.
How long can a video be on X?
Per X's API media documentation, a video on a post can run from half a second to 20 minutes and 8 GB on a free account, and up to 125 minutes and 16 GB for Premium or verified accounts. The old 2 minutes 20 seconds figure is out of date. The aspect ratio must sit between 1:3 and 3:1.
How long can a YouTube Short be?
YouTube's help centre describes Shorts as short-form videos up to 3 minutes long. The older 60 second limit no longer applies. A video longer than three minutes is uploaded as a regular video instead.
Is my video uploaded when I use this checker?
No. Your browser opens the file with a hidden video element and reads the duration, dimensions and file size on your device. Nothing is sent to TimeToPost or anyone else, so unreleased footage stays private. Closing the tab discards it.
What if the tool cannot read my file?
Some codecs, such as certain HEVC or ProRes files, will not play in every browser, and a browser that cannot play a file cannot report its length. The tool says so instead of guessing and offers manual mode, where you type the duration and dimensions from your editor.
Why does TikTok have no fixed length here?
TikTok's Content Posting API states that different creators have different maximum video durations, and the app shows yours. This checker starts at 300 seconds, the example in TikTok's docs, and marks it approximate. Type your own maximum to get an exact answer.