Mastodon header size
1500 × 500px
Aspect ratio
3:1
Mastodon headers are exactly 1500 × 500 px (3:1) — the official docs confirm uploads are downscaled to that size.
Last verified June 2026
The Mastodon header is one of the few specs on this list with an official, documented number: per the Mastodon documentation, header uploads (WEBP, PNG, GIF, or JPG, up to 2 MB) are downscaled to 1500 × 500 px — a 3:1 banner across the top of your profile. Design at exactly that size and what you export is what federated viewers see, give or take each client’s slight crop differences.
| Variant | Dimensions | Ratio |
|---|---|---|
| Header (official) | 1500 × 500 pxPer docs.joinmastodon.org — uploads are downscaled to this. | 3:1 |
| Upload ceiling | any, ≤2 MBLarger-dimension files are accepted and resized down to 1500 × 500. | — |
| Display crop | variesWeb, mobile apps, and third-party clients trim edges slightly differently. | ~3:1 |
In the official web profile, the avatar and display name overlay the lower-left of the header, and mobile clients pinch the visible area tighter than desktop. Keep text and logos in the upper-center region, clear of the bottom-left quadrant and the outer 10% on each side. Because dozens of third-party apps render profiles their own way, a centered composition with no edge-critical content is the only design that looks right across the whole fediverse.
Mastodon has no algorithmic recommendation engine pushing your account — people decide to follow from your profile, often after one good post got boosted into their timeline. A header that states the account’s beat in plain type (“Open-source design notes, weekly”) converts that visit better than abstract art, because it answers the one question a visitor has: what will following this account get me?
Animated headers feel fun but play inconsistently across clients, and any detail near the edges gets trimmed somewhere in the app ecosystem. Build the design as a static 1500 × 500 with the message centered; if you want motion, let a subtle looping GIF background sit behind type that reads perfectly as a still frame.
On Mastodon your profile shows which server you call home, and server culture is part of your identity there. Brands generally do best with a clean branded header consistent with their other platforms (the 3:1 ratio matches X and Bluesky, so one master file serves all three) — just confirm nothing important sits where Mastodon’s avatar overlay lands.
1500 × 500 px at 3:1 — this one is official: the Mastodon docs state header uploads up to 2 MB are downscaled to exactly that size. Design at native size for a pixel-perfect result.
Yes, GIF is an accepted format on most servers — but animation playback varies by client, and the 2 MB cap arrives fast for animations. Make sure the first frame works as a standalone still.
The fediverse has many clients, and each renders profiles slightly differently — overlay positions and edge crops vary. Keep the message centered and away from the bottom-left avatar zone and it will read correctly everywhere.
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