Mastodon image & video sizes
Mastodon accepts a range of image sizes (limits can vary by instance). A landscape image up to about 1920 × 1080 is a safe default; remember to add image descriptions.
TypeDimensionsRatio
Image1,920 × 1,080 px16:9
Profile photo400 × 400 px1:1
Header1,500 × 500 px3:1
Recommended sizes as of 2026. Networks adjust specs and some accept a range — verify the current size before publishing.
FAQ
Mastodon sizes, answered
What image size does Mastodon use?
Mastodon is flexible and limits can vary by instance; a landscape image up to roughly 1920 × 1080 px is a safe default. Add alt text — the community values accessibility.
What is the Mastodon header size?
A 1500 × 500 px (3:1) header is a common, safe choice.
Size it, then schedule it
Compose, preview natively at the right size, and schedule Mastodon posts — free.