Mastodon avatar size
400 × 400 px · 1:1 · avatar
400 × 400
The details
Mastodon downscales avatars to 400×400 (WEBP, PNG, GIF or JPG, up to 2MB), so uploading exactly 400×400 avoids resampling entirely. Individual servers can configure different limits.
Source: docs.joinmastodon.org · checked 2026-07-04