How it works
Substack's built-in editor is clean but limited — there's no way to preview your post with the exact fonts, line spacing, and email client rendering before publishing. The Substack Post Formatter lets you write or paste your post, apply Substack-compatible formatting (headers, pullquotes, dividers, bold, italic, hyperlinks), preview it in a realistic Substack email mockup, and copy the formatted text for paste into Substack's editor.
Features: - Pull quote block: wrapped in Substack's distinctive quotation style — ideal for highlighting key stats or memorable lines - Section divider: three-em dash divider matching Substack's style - Email preview mockup: shows exactly how the post renders in a typical email client (Gmail inbox width, system font rendering) - Character and word count: per-section and total — useful for hitting ideal newsletter length (800–1,200 words for weekly letters, 300–500 words for brief daily notes) - Reading time estimate: words divided by 238 (average adult reading speed) equals estimated reading minutes
Substack-specific formatting tips: - Bold the most important sentence in each section — scanning readers stop at bold text - Keep paragraphs to 3 sentences maximum for email readability - Use section headers (H2) to help readers navigate long issues - The subject line and preview text carry the highest open-rate weight — make them count
How to use: 1. Paste or write your post in the editor panel. 2. Use the toolbar to apply formatting — changes appear live in the preview panel. 3. When satisfied, click "Copy Formatted Text" and paste into Substack's editor.
Privacy: all formatting runs in the browser. Your content is never transmitted.
Frequently Asked Questions
- This tool's preview panel renders at a width of 600px — the standard Gmail desktop reading pane width — using system fonts (Georgia for body, similar to how email clients render Substack's default font). For a pixel-perfect preview, send a test draft to yourself via Substack's Send Test Email feature before publishing. Note that Gmail, Apple Mail, and Outlook render fonts slightly differently — the tool represents the Gmail rendering.
- Substack's internal data suggests posts between 800–1,200 words have the highest open-to-read-through rate (the percentage of openers who read more than 80% of the post). Shorter posts (under 400 words) have high read-through rates but lower perceived value. Longer posts (2,000+ words) have lower read-through rates but work well for monthly deep-dives where the audience expects depth.
- Both simultaneously is the default and recommended approach. Publishing to both email and web maximises reach (email delivers to existing subscribers, web allows new discovery via search and social sharing) and builds an archive of indexed content. Publishing web-only is an option for teaser posts or free content on a paid newsletter; publishing email-only creates exclusivity for paid tiers but sacrifices SEO value.
- The highest-engagement Substack features are: Recommendations (readers of similar newsletters discover yours), Notes (Twitter-like micro-posts that keep the audience engaged between issues), Chats (threaded community discussions per post), and paid subscription tiers with exclusive content. The Reply rate (how many subscribers reply to an issue) is the highest-quality engagement signal on Substack — a post that generates 20 replies has more value than one with 500 likes.