Will your post
actually publish?
Drop in a video or image and see whether it fits every platform's length, size, and aspect ratio rules. Your file is read in your browser and never uploaded.
Your file is read in your browser. It is never uploaded, stored, or sent anywhere.
Placement fit
Choose a file above to see which placements it fits.
Where these limits come from
These are the rules Picmim enforces when publishing through each platform's official API. Each one links to the platform's own documentation so you can check it yourself.
- Instagram Reel Instagram Platform documentation — Reels publishing
- Instagram Story Instagram Platform documentation — Stories publishing
- Facebook Story Meta Page Stories API documentation
- YouTube Short YouTube Help — Create a Short
- TikTok video TikTok Content Posting API — media transfer guide
- Instagram feed image Instagram Platform documentation — image publishing
- Facebook feed image Meta Graph API — photo publishing
- X image X API — media upload limits
- LinkedIn image LinkedIn Marketing API — image ads and shares
- Bluesky image Bluesky API — posting images
- Pinterest Pin Pinterest API — creating Pins
- Threads image Threads API — media publishing
- TikTok image TikTok Content Posting API — photo posts
Ready to schedule that video?
Picmim checks these rules before you publish, so a clip that will not post never reaches your calendar. Schedule to every platform from one place.
Get started with Picmim →Frequently asked questions
Is my video uploaded anywhere?
No. The file is read on your own device using your browser's built-in media decoder, and the duration and dimensions never leave it. Nothing is uploaded, stored, or sent to Picmim — we only record that a check happened, never anything about the file.
How long can an Instagram Reel be?
Picmim publishes Reels between 3 seconds and 15 minutes (900 seconds). Instagram Stories are shorter, between 3 and 60 seconds, and a longer clip is split or rejected rather than trimmed automatically.
How long can a YouTube Short be?
Up to 3 minutes (180 seconds). Anything longer is published as a standard video rather than a Short, which changes how it is surfaced.
What are the image size limits?
Byte limits vary widely: Bluesky allows 1MB, Facebook 4MB, X 5MB, Instagram and Threads 8MB, LinkedIn and TikTok 10MB, and Pinterest 20MB. Going over the byte limit does not block the post — Picmim compresses the image before sending it — but the result loses some quality, so the checker flags it.
Why does the aspect ratio only warn instead of failing?
Because platforms crop rather than reject. A 1:1 video still posts as a Reel — it is just letterboxed or cropped, which usually looks worse than intended. The checker flags it so the decision is yours.
Are these limits up to date?
They mirror the rules Picmim enforces when publishing through each platform's official API, and every placement lists the exact source it came from. That is a stronger guarantee than a blog post, because these values are the ones our publishing pipeline actually uses.