Compress Images for Substack — Free & Instant
Substack newsletter images are embedded in email and displayed on web. Images must be optimized for both email clients and web browsers, with email-safe formats prioritized. Use ImageSmith's free image optimizer to compress your Substack images directly in your browser — no account needed, no watermarks, and no ads. Target under 10,000KB per image for best results on Substack.
Max File Size
10,000 KB
Recommended Format
JPEG
Dimensions
1200×675 for newsletter cover images
Substack Compression Tips
- 1.Email subscribers see compressed images — pre-optimize for email quality
- 2.Keep email-embedded images under 200KB for reliable delivery
- 3.Use JPEG for photographs — Substack email clients do not support WebP
- 4.Cover images display at 1200×675 in web and email previews