Image size limits on X (Twitter), Bluesky, Mastodon and Telegram
Check how many images and how large a file each network takes, crop so the subject stays in view, and export one set of files that fits all four networks.
An image can be up to 5 MB on X (Twitter), 2 MB on Bluesky and 16 MB on Mastodon, and each of the three takes up to four images per post. A Telegram bot can send an album of up to ten photos, each up to 10 MB. Export every image as a JPEG or PNG under Bluesky’s 2 MB, and one set of files fits all four.
This guide covers choosing, cropping, exporting and describing still images. GIFs follow other rules, covered in the GIF guide.
The image limits at a glance
| Network | Images per post | Size per image | Also check |
|---|---|---|---|
| X (Twitter) | Up to 4 | 5 MB | JPG, PNG, GIF or WEBP |
| Bluesky | Up to 4 | 2 MB (2,000,000 bytes) | Older guides still say 1 MB |
| Mastodon | Up to 4 by default | 16 MB | Downscaled to 8.3 megapixels |
| Telegram, through a bot | 1, or 2 to 10 as an album | 10 MB, or 5 MB when sent from a link | Width plus height at most 10,000 px |
| Misskey | Set by your server | Set by your server | Your server’s own rules |
The figures come from X (Twitter)’s media best practices for its API, Bluesky’s image format, Mastodon’s posting guide and Telegram’s Bot API. Limits change, so recheck them. For your Mastodon server’s own figures, open https://your.server/api/v2/instance and find max_media_attachments and image_size_limit (in bytes).
Decide how many images the post needs
With more than four photos, choose the four that matter most, or put the rest in a reply that continues the post. The thread guide covers keeping replies in order. A Telegram album can hold up to ten.
A made-up market stall photographs six pieces from a new ceramics batch for X (Twitter), Bluesky, Mastodon and its Telegram channel. Its phone photos are 6 to 9 MB each. The plan:
- Main post: the four strongest pieces, with the new mug first.
- Reply: the other two pieces.
- Telegram channel: all six as one album, in the same order.
Put the image that explains the post first, and keep any series of steps in order.
Crop so the subject stays in every preview
Networks and apps crop timeline previews differently, from squares to wide strips. Prepare each photo for all of them:
- Put the subject near the center, with space around it.
- Keep text, prices and logos away from the edges.
- Don’t split one wide picture across several images; the parts won’t line up in every layout.
- Check the preview in each composer before you post.
Mastodon also lets you set a focal point on each image, which can improve previews that aren’t shown at 16:9. The stall photographs each piece centered against a plain cloth, so most crops show all of it.
Export each image under 2 MB
Export for Bluesky’s 2 MB, the strictest size, and the other three networks take the files too. Use JPEG for photos and PNG for screenshots with small text, since JPEG blurs the edges of letters. Resize photos to about 2,000 pixels on the long edge, as the stall does. A JPEG of that size usually fits under 2 MB at medium-high quality; if not, lower the quality a step. Crop an oversized screenshot to the part that matters.
Check the size in bytes. Some file managers, such as Windows File Explorer, count a megabyte as 1,048,576 bytes, so a file listed there as 1.95 MB is about 2,044,700 bytes: over Bluesky’s limit. The file’s properties or info window shows the exact count.
Before uploading, remove location data you don’t want to share.
Describe every image, in order
Write one description per image, and say which step each one shows when the images are a sequence. When you swap or reorder an image, move its description with it.
X (Twitter), Bluesky and Mastodon keep a description with each image. A bot can’t attach a description to a Telegram photo, so put anything essential in the caption.
The stall’s first photo gets: “Speckled blue mug, front view, with a thumb rest on the handle.” The alt text checklist covers what to write.
Publish and check the images
After publishing, open each post on each network and check:
- Count: every image arrived, and the reply holds the rest.
- Order: the same on every network.
- Crop: the subject shows in the timeline preview.
- Quality: screenshot text is readable at full size.
- Descriptions: each belongs to its image.
- Telegram: all the photos sit in one album, in order.
In Studio, a note holds up to 10 pictures, each under 20 MB, and you can add only as many as every selected network takes, such as four with X (Twitter) or Bluesky. If you select a network that takes fewer after adding them, Studio shows “Too many images for the selected platforms”. To reorder pictures, drag them or press Alt and an arrow key. Each has a description and a “Sensitive” switch. “Add to thread” puts extra pictures in a follow-up. Studio isn’t available yet, but you can join the waitlist.
