Media requirements
Every size each network accepts, drawn at its real proportions — plus what happens when a file is the wrong shape.
Sizes by network
One block per network, every size it takes drawn together. A green tick means we published that exact size and watched it land; a red cross means it was refused. Sizes without a mark are the standard recommendation.
The feed takes anything from 3:4 down to 1.91:1. Outside that it is refused outright — never cropped for you.
TikTok
Video is vertical. Photos keep whatever ratio you upload — nothing is cropped.
YouTube
Horizontal is a video, vertical under 3 minutes is a Short. Same upload either way.
Pages only. Reels are vertical and run 3 to 90 seconds.
Up to 20 images or one video — never both in the same post.
X (Twitter)
Up to 4 images or a single video. Landscape shows largest in the timeline.
Threads
Follows Instagram’s shapes. Carousels take up to 20 items.
Networks with no shape rules
Bluesky, Mastodon, Discord, Telegram, Tumblr, DEV Community, WordPress publish whatever you give them. Upload the shape you want people to see — nothing is cropped or re-encoded on the way, except Bluesky images over 1 MB, which we compress for you.
What we fix for you
Some limits are ours to absorb. These four are handled before your file reaches the network.
Instagram Story fitting
A non-9:16 image is rendered onto a 1080×1920 canvas over a blurred copy of itself, so the whole frame survives instead of being centre-cropped. Scheduled and API posts get the same treatment server-side, with a solid black pad.
Bluesky compression
The protocol caps a blob at 1 MB. Anything larger is downscaled and re-encoded until it fits, rather than failing the post.
External media ingest
A post created with a public image or video URL has that file pulled onto our CDN first. Networks that reject unstable third-party URLs then see a stable one.
Large video streaming
Uploads run to 500MB from the app and up to 4 GB through a presigned URL. Video is streamed to the network rather than buffered, so a large file never has to fit in memory at once.
All the numbers
We never block an upload for its shape — the networks disagree with each other and change their minds, so we recommend and let the file through. Uploads cap at 500MB per file in the app, or 4 GB through a presigned URL, which is the better path for video. Storage is metered per seat; see Plans & quotas.
Media given as a public URL is copied to our CDN before publishing, so a link that dies between scheduling and publishing can’t take the post down with it. Details in the Media API reference.