How to do it
- Choose the network Pick where the image will be posted first.
- Choose the format Feed image, link preview, or thumbnail. Each has its own ratio.
- Read the size and ratio Export at the listed pixel size. The ratio matters more than the exact pixels.
- Check the safe zone Keep faces and text away from the edges that the feed crops on mobile.
Recommended image sizes by network
These are the sizes that display without awkward crops in 2026. Networks resize anything you upload, so the aspect ratio matters more than the exact pixel count.
| Network | Format | Size (px) | Ratio |
|---|---|---|---|
| X | Landscape post | 1600 x 900 | 16:9 |
| X | Square post | 1080 x 1080 | 1:1 |
| X | Link card | 1200 x 628 | 1.91:1 |
| Square post | 1200 x 1200 | 1:1 | |
| Vertical post | 1080 x 1350 | 4:5 | |
| Link preview | 1200 x 627 | 1.91:1 | |
| Bluesky | Post image | at least 1000 on the short side | 1:1, 4:5, 3:4, 16:9 |
| Bluesky | Link card | 1200 x 627 | 1.91:1 |
| Mastodon | Post image | 1280 x 720 | 16:9 |
| Threads | Vertical post | 1440 x 1920 | 3:4 |
| Threads | Square post | 1080 x 1080 | 1:1 |
| Vertical post | 1080 x 1350 | 4:5 | |
| Square post | 1080 x 1080 | 1:1 | |
| Vertical post | 1080 x 1350 | 4:5 | |
| Link preview | 1200 x 630 | 1.91:1 | |
| YouTube | Thumbnail | 1280 x 720 | 16:9 |
File size limits that catch people out
- Bluesky accepts images up to about 1 MB each, up to 4 per post. Export JPEG at 80 to 85 percent quality or the upload fails.
- Mastodon limits are set per instance. Many allow around 16 MB, and very large images are downscaled.
- X accepts up to 4 images per post, with a 5 MB limit for photos.
One image, many networks
If you post the same image everywhere, a 4:5 vertical at 1080 x 1350 is the safest single choice for feeds, and a separate 1.91:1 image covers link previews. Keep text inside the central 80 percent so mobile crops do not cut it.
Alt text is part of the image
Every network on this list lets you add alt text. Write one or two sentences that say what the image shows and why it matters. See the alt text glossary entry.
Posting images with SocialHandoff
SocialHandoff publishes images to X, LinkedIn, Bluesky, Mastodon, Threads, Instagram, and Facebook, with alt text where the network accepts it, and photo posts to TikTok. YouTube is not supported yet; its sizes are here for reference. A missing-alt-text guardrail can flag drafts before they reach your inbox. See the Bluesky, Mastodon, and Instagram scheduling guides or the LinkedIn carousel caption template.