Compress image for Substack Publication Header
Substack publication headers render up to 1600 px wide. Uploads at that dimension avoid Substack's own re-encoding.
Your images stay on your device. Nothing is uploaded.
Substack's publication customisation lets you upload a header image (also called the 'newsletter cover'). It renders at up to 1600 px wide on desktop, downscaled on mobile.
JPEG is the safe format for the publication header — some Substack email templates surface it in the email itself, and email-client compatibility rules apply.
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Frequently asked questions
- What size should an image be for Substack publication header?
- The preset on this page reflects the recommended dimensions for Substack publication header. Uploading at these dimensions avoids the auto-crop or auto-downscale that the platform would otherwise apply.
- Does the platform re-encode after upload?
- Yes — most platforms re-encode uploaded images to their internal format and bitrate. Starting from a clean, correctly sized image means only one round of lossy re-encoding rather than two.
- What format should I use for Substack publication header?
- The preset uses the format recommended for Substack publication header. JPEG is the safest universal choice; some workflows benefit from WebP or PNG for specific reasons (transparency, screenshots, etc.).
- Is anything uploaded?
- No. The compression and resize run in your browser. The image only leaves your device when you upload it to Substack publication header yourself.
- Can I batch process multiple images for Substack publication header?
- Yes — use the bulk compressor to process a folder of images with the same settings. Every image gets the correct dimensions and quality for Substack publication header.
Prepare a Substack — publication header image.
Drop your image — the tool applies the correct dimensions and quality for the platform.
Start compressing