Substack post preview image size
1456 × 1048 px · 1.39:1 · cover
1456 × 1048
The details
The cover image on a post and the card that social networks and the Substack app show when it's shared. Substack recommends at least 1456×1048 (about 14:10); the stated minimum is 420×300.
Source: support.substack.com · checked 2026-07-04