Social media video validator
Pick a video and instantly see whether it fits every platform's post, Reel/Short and Story limits — length, file size, orientation and aspect ratio — with the exact reason when it doesn't.
Limits come from the same rules Join Postly uses when publishing. See every limit on the post & upload limits page.
Frequently asked questions
Is my video uploaded anywhere?
No. The validator reads the file's duration, resolution, size and type directly in your browser. The video never leaves your device, so it works for large files and private content.
What is the best video format for social media?
MP4 with H.264 video and AAC audio is accepted almost everywhere. Use 1080 × 1920 (9:16) for Reels, Shorts, TikTok and Stories, and 1920 × 1080 (16:9) for regular YouTube, X and LinkedIn videos.
Why does my video pass on one platform but fail on another?
Each network sets its own limits. For example, Instagram Stories take videos up to 60 seconds, YouTube Shorts up to 3 minutes and must be vertical, and X accepts up to 140 seconds. The table shows the exact reason for every failure.
The tool says the duration is unknown. What should I do?
Your browser couldn't decode the video, which often happens with HEVC (H.265) files from iPhones. Re-export it as MP4 (H.264) and check again — that also makes it compatible with more platforms.
Can Join Postly publish one video to several platforms?
Yes. Upload once (files up to 1 GB, with resumable uploads) and Join Postly checks each selected account against these same rules before scheduling, so nothing fails at publish time.
Schedule it with Join Postly
Upload once, publish everywhere. Join Postly checks every video against each platform before it goes out.