Last updated: April 28, 2026

Mastodon Image Size Cheat Sheet 2026

Q: What is the Mastodon avatar size?

Mastodon avatars should be 400x400 pixels. Supported formats include PNG, JPEG, and GIF (including animated). The maximum file size is typically 2 MB, though this can vary by instance. The avatar is displayed as a circle.

Q: What is the Mastodon header size?

Mastodon headers should be 1500x500 pixels (3:1 aspect ratio). This matches the same dimensions as X/Twitter headers. PNG, JPEG, and GIF formats are supported up to 2 MB on most instances.

Q: Does Mastodon support animated profile images?

Yes. Most Mastodon instances support animated GIF avatars and headers. However, some instances disable animation by default to reduce bandwidth. Users can toggle animation display in their preferences.

Q: Are Mastodon image limits the same across all instances?

No. Mastodon is decentralized, so each instance can set its own limits. Current Mastodon defaults allow 2 MB avatars and headers, 16 MB image attachments, and larger video attachments, but individual admins can adjust these.

Q: What size should Mastodon post images be?

Mastodon accepts images up to 16MB and downscales large images to about 8.3 megapixels, enough for a 3840x2160 attachment. Preparing images at or below that size avoids unnecessary upload weight.

Mastodon uses 400x400 avatars and 1500x500 headers, and it downscales large post images for delivery across federated instances. Because each instance can set limits, the safest workflow is to crop to the expected dimensions and compress before upload. FastEdit prepares profile images, post images, and short animated media locally in your browser.

Start editing Mastodon Avatar

Pick this preset, drop your file, and FastEdit starts from the Mastodon Avatar dimensions, format, and file-size target.

Mastodon Image Size Cheat Sheet

Avatar

400x400 PNG / JPEG / GIF Max 2 MB

Profile picture shown as a circle in most themes. Animated GIFs are supported on most instances. Keep subjects centered.

Open Mastodon Avatar preset →

Header

1500x500 PNG / JPEG / GIF Max 2 MB

Profile page banner at 3:1 ratio. Displayed behind the avatar and bio. Animated headers (GIF) are supported on most instances.

Open Mastodon Header preset →

Post Image

3840x2160 PNG / JPEG / WEBP / AVIF Max 16 MB

Large 16:9 attachment size that stays within Mastodon's image downscale target. Useful for screenshots, artwork, and announcement graphics.

Animated GIFV Source

1280x720 GIF / MP4 / WebM Max 16 MB

Safe animated-media target for looping GIF-style posts. FastEdit can trim, resize, and export short clips before upload.

What can you create for Mastodon?

Use these rows when you know the asset you need but not the exact settings. Each one points to the matching FastEdit workflow.

How to prepare Mastodon Avatar

Open FastEdit with the Mastodon Avatar preset selected, drop your file, then export to this row's target: 400x400, PNG / JPEG / GIF, max 2 MB.

mastodon avatar sizemastodon avatar dimensionsresize mastodon avatarcreate mastodon avatar

Open Mastodon Avatar preset →

How to prepare Mastodon Header

Open FastEdit with the Mastodon Header preset selected, drop your file, then export to this row's target: 1500x500, PNG / JPEG / GIF, max 2 MB.

mastodon header sizemastodon header dimensionsresize mastodon headercreate mastodon header

Open Mastodon Header preset →

How to prepare Mastodon Post Image

Use this Mastodon cheat-sheet row as the target spec: resize or trim to 3840x2160, export as PNG / JPEG / WEBP / AVIF, and keep the file at 16 MB.

mastodon post image sizemastodon post image dimensionsresize mastodon post imagecreate mastodon post image

How to prepare Mastodon Animated GIFV Source

Use this Mastodon cheat-sheet row as the target spec: resize or trim to 1280x720, export as GIF / MP4 / WebM, and keep the file at 16 MB.

mastodon animated gifv source sizemastodon animated gifv source dimensionsresize mastodon animated gifv sourcecreate mastodon animated gifv source

Before you upload

Most Mastodon instances support animated GIF avatars and headers: check your instance settings for specific limits.
Avatar images are typically displayed as circles, matching the same style as X/Twitter and other social platforms.
Header images may be cropped differently depending on the Mastodon web client or app being used: keep content centered.
Profile image limits can vary by instance: 2 MB is a safe maximum for avatars and headers on most servers.
For post attachments, add alt text in Mastodon after upload. FastEdit prepares the file; Mastodon stores the media description.

FAQ

What is the Mastodon avatar size?

What is the Mastodon header size?

Does Mastodon support animated profile images?

Are Mastodon image limits the same across all instances?

What size should Mastodon post images be?