SVG vs PNG for Substack

Substack content reaches readers through both a web page and an email inbox — and those two contexts handle SVG very differently.

The Email Client Compatibility Problem

Substack posts are delivered as both a web page and an email newsletter — and while modern browsers render SVG in the web version fine, many email clients (particularly Outlook and some webmail providers) have poor or no SVG rendering support, potentially showing broken images to a meaningful portion of your subscriber base.

Web view rendering of SVG works fine in modern browsers
Email client SVG support is inconsistent, especially in Outlook
A portion of subscribers reading via email may see broken images

Why PNG Is the Safer Newsletter Choice

Given email's inconsistent SVG support, export diagrams, illustrations, and header graphics as PNG for Substack posts — this guarantees every subscriber sees the intended image whether they're reading in the web archive or their email inbox, avoiding the broken-image risk that direct SVG embedding carries for email recipients specifically.

PNG export guarantees consistent rendering across web and email
Avoids broken-image risk for the meaningful email-reading subscriber segment
Export from a vector source at 2x size to maintain crispness in the PNG

Frequently Asked Questions

Does Substack's web archive support SVG even if email doesn't?

The web-based version of a Substack post generally renders SVG fine in modern browsers — the compatibility concern is specifically about the email delivery to subscribers' inboxes, where client support varies significantly.

What resolution should newsletter PNG images be?

Export at roughly 2x the display width used in the newsletter layout, keeping images sharp on high-density phone and desktop screens without becoming unnecessarily large in file size for email delivery.

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