Mastodon Image Sizes
Mastodon image sizes for 2026 — posts, header, and avatar.
| Format | Size (px) | Ratio | Notes |
|---|---|---|---|
| Post image | 1280 × 720 | 16:9 | Images over ~8 MB are downscaled server-side. |
| Square post | 1080 × 1080 | 1:1 | Good for graphics and quotes. |
| Profile header | 1500 × 500 | 3:1 | Banner at the top of your profile. |
| Avatar | 400 × 400 | 1:1 | Shown as a rounded square. |
Resize to these sizes
Crop your image to Mastodon's exact dimensions.
Compress for upload
Shrink the file so it uploads crisp, not blurry.
Remove background
Clean profile and product shots in one click.
Image sizes for other platforms
Bolta writes your platform-sized posts in your brand voice, automatically — and waits for your approval before posting.
This page is a spec sheet, not a tool. Bolta applies the spec for you — every post, every platform, without the lookup.
From correct size to published post
Knowing the size is step one. Bolta formats your content to Mastodon's spec automatically and publishes it across every platform from one place.
Reuse It Intentionally
Adapt your core content for multiple formats, angles, and platforms instantly.
Automate Future Schedules
Build a consistent posting plan that stays active even when you're busy.
Turn It Into a Loop
Put your content on autopilot with automated variations and recurring schedules.
Frequently asked questions
What is the best image size for Mastodon posts?
What aspect ratios does Mastodon support?
Why does my Mastodon image look blurry or cropped?
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