Image Sizes for X (Twitter), Bluesky, and Mastodon in 2025
Exact image dimensions for X/Twitter, Bluesky, and Mastodon. Quick reference guide with optimal sizes, file limits, and format recommendations for each platform.
Wrong image sizes mean cropped faces, cut-off text, and unprofessional posts. Here are the exact dimensions you need for X (Twitter), Bluesky, and Mastodon—no filler, just the numbers that work.
Quick Reference Table
| Platform | Single Image | Profile Picture | Header/Banner |
|---|---|---|---|
| X/Twitter | 1200 × 675px | 400 × 400px | 1500 × 500px |
| Bluesky | 1200 × 675px | 300 × 300px | 1500 × 500px |
| Mastodon | 1280 × 720px | 400 × 400px | 1500 × 500px |
Save this table. Now let's break down what actually matters for each platform.
X (Twitter) Image Specifications
Standard Posts
Optimal size: 1200 × 675 pixels (16:9 aspect ratio)
This dimension displays without cropping in both timeline view and expanded view. Anything narrower gets letterboxed; anything taller gets cropped to show the center.
File requirements:
Safe zone for text: Keep important text within the center 80% of your image. Mobile users see less of the edges.
Multiple Images
X handles multi-image posts differently depending on count:
Two images: Each displays at roughly 7:8 aspect ratio. Vertical images work better here than horizontal.
Three images: First image takes the left half, remaining two stack on the right. Make your strongest image the first one.
Four images: 2×2 grid, equal sizing. Square or nearly-square images work best.
Pro tip: When posting multiple images, preview on mobile before publishing. X crops aggressively on smaller screens.
Profile and Header
The header's bottom portion gets covered by your profile picture on desktop. Keep text and key visuals in the top two-thirds.
For complete X posting strategies, see our guide to scheduling posts on X/Twitter.
Bluesky Image Specifications
Standard Posts
Optimal size: 1200 × 675 pixels (16:9 aspect ratio)
Bluesky follows similar conventions to X, making cross-posting easier. The platform converts uploads to efficient formats automatically.
File requirements:
The 1MB limit catches people off guard. If your image exceeds it, reduce quality to 75-80% or resize to 1000px width.
Multiple Images
Maximum: 4 images per post
All images display in a grid layout with 4px spacing. Square formats (1:1) work consistently across 2, 3, and 4-image layouts.
Recommended multi-image size: 1200 × 1200px per image
Profile and Header
Bluesky's header displays slightly differently than X—test your header on both desktop and mobile apps.
For Bluesky-specific tips, check our complete Bluesky scheduling guide.
Mastodon Image Specifications
Mastodon's federated structure means limits vary by instance. These specs work across most instances:
Standard Posts
Optimal size: 1280 × 720px (16:9 aspect ratio)
Mastodon is more forgiving than X or Bluesky—larger images work fine, and the platform handles resizing gracefully.
File requirements:
Multiple Images
Maximum: 4 images per post (some instances allow up to 8)
Mastodon uses a flexible grid that adapts to image aspect ratios. Unlike X, it doesn't force aggressive cropping.
Alt Text Matters Here
Mastodon's community expects alt text on images. Many users filter out posts without it. Keep descriptions under 1500 characters and focus on what matters:
This isn't optional politeness—it's how Mastodon works. Posts with thoughtful alt text consistently get more engagement.
Profile and Header
Instance admins can change these limits. If your uploads fail, check your instance's documentation.
For Mastodon-specific strategies, see our Mastodon scheduling guide.
Practical Workflow for Multi-Platform Posting
If you're posting to multiple platforms—which saves significant time—here's what actually works:
The Universal Size
1200 × 675px works on all three platforms without cropping. This is your default.
Use this for:
When to Deviate
Go square (1200 × 1200px) when:
Go taller (1200 × 1500px) when:
Just know X will crop taller images in timeline view—users tap to see the full thing.
Resizing Without Quality Loss
You don't need Photoshop for this. Mac users can batch resize in Preview with no extra software:
For quick dimension checks before posting, use our image resizer tool. It shows you exactly how your image will appear on each platform.
File Size Optimization
When images exceed platform limits:
For photos (JPEG):
For graphics with text (PNG):
Statuz automatically handles media optimization during upload—it adjusts format and compression to meet each platform's requirements while preserving visual quality. Check supported formats and limits for specifics.
Common Mistakes That Kill Engagement
Uploading straight from camera: A 12MB photo will either fail to upload or load slowly for viewers. Always resize first.
Ignoring mobile preview: 80%+ of social media browsing happens on phones. What looks perfect on your 27" monitor might be illegible on a 6" screen.
Text too small: If you're adding text to images, minimum 24px for headlines, 16px for body text. Test by viewing at 50% zoom—still readable?
Wrong aspect ratio for the content: Vertical subjects (people, buildings) in horizontal frames waste space. Match aspect ratio to content.
Skipping alt text on Mastodon: Your post literally won't reach users who filter for accessibility. Two sentences of description takes 10 seconds.
Platform-Specific Tips That Actually Help
X/Twitter
Bluesky
Mastodon
The Sizes Worth Memorizing
For 90% of posts: 1200 × 675px For profiles: 400 × 400px (or 300 × 300px for Bluesky) For headers: 1500 × 500px For multi-image: 1200 × 1200px
Everything else is edge cases. Get these four right, and your images will display correctly across X, Bluesky, and Mastodon.
Streamline the Process
Manually resizing every image gets old fast. A few ways to speed this up:
Finder tags: Color-code images by platform so you know which version is which. Here's how to set that up.
Smart folders: Create Finder smart folders that automatically collect images by size or date modified.
Template files: Keep blank canvas files at each platform's dimensions. Drag your content in, export, done.
Native tools: Statuz handles image optimization automatically during the posting process. Drop in any image, and it adjusts dimensions and file size for each platform you're posting to. One upload, optimized for everywhere.
Ready to simplify your cross-platform posting? Check our guide on cross-posting between X, Bluesky, and Mastodon, or download Statuz to handle the technical details automatically.