Substack Post Character Limit: 10,000 Characters
Last updated June 2026
The Substack character limit is 10,000 characters per post — the official current limit as of 2026. Ferryman caps Substack Notes at 10,000 characters to keep cross-posted Notes reliable.
How Substack's limit compares to other platforms
| Platform | Character limit | Native threading |
|---|---|---|
| Substack | 10,000 | No |
| X | 280 | Yes |
| Bluesky | 300 | Yes |
| Threads | 500 | Yes |
| Mastodon | 500 | Yes |
| 3,000 | No | |
| 63,206 | No |
Substack's 10,000-character limit sits in the middle of the major text platforms — more generous than X's standard limit, tighter than LinkedIn's. Most Substack posts cross-post cleanly to platforms with similar limits, and require thread splitting on platforms with shorter ones.
What happens when you go over 10,000 characters
Substack doesn't have native threading the way X or Bluesky do. Posts longer than 10,000 characters can't be split into a thread automatically — they need to fit in a single post. Fortunately, 10,000 is generous enough that most cross-posted content (even longer Threads or Mastodon posts) lands as a single post without truncation.
Other Substack character limits (bio, comments, and more)
The 10,000-character cap applies to posts. Substack sets separate limits for the rest of your profile and activity (all figures current as of 2026):
| Field | Character limit |
|---|---|
| Post | 10,000 characters |
| Publication post | Long-formSubstack newsletter posts are a different format from Notes |
| Comment | 10,000 charactersFerryman uses the same Notes-safe cap |
Substack media and threading limits
- Images per post: 10
- Alt text on images: Not supported
- Video: Supported, up to 600 seconds
- Native threading: No — long content must fit in one post
Cross-posting and the Substack character limit
Substack is supported as a destination in Ferryman. Posts from X, Bluesky, Threads, Mastodon, LinkedIn, Facebook can be cross-posted to Substack, and Ferryman keeps them within Substack's 10,000-character Notes-safe limit.
Frequently asked questions
What is the Substack character limit in 2026?
Substack's character limit is 10,000 characters per post. Ferryman caps Substack Notes at 10,000 characters to keep cross-posted Notes reliable.
Can I post longer than 10,000 characters on Substack?
No — Substack doesn't support a way to post longer than 10,000 characters as a single post or thread. If you need more length, consider a different platform or format (like an article or document attachment).
How does Substack's character limit compare to X?
Substack's 10,000-character limit is 9,720 characters longer than X's 280. Posts that fit on X always fit on Substack.
How does Substack's character limit compare to Bluesky?
Substack's 10,000-character limit is 9,700 characters longer than Bluesky's 300. Posts that fit on Bluesky always fit on Substack.
How does Ferryman handle the Substack character limit when cross-posting?
Ferryman watches your origin platform for new posts and replicates them to Substack. If your source post fits in 10,000 characters, it cross-posts as a single Substack post. If it doesn't, Ferryman keeps the post on platforms where it fits and notes the skip on your Posts page.
Learn more about Substack
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