The default character limit for a Mastodon post is 500 characters.
Mastodon is a decentralized, open-source social network that is part of the Fediverse. Unlike centralized platforms, each Mastodon instance (server) can set its own character limit. The default is 500, but some instances allow up to 5,000 or more.
Character limits on Mastodon
| Content type | Default limit |
|---|---|
| Post (toot) | 500 characters |
| Content warning (CW) | 500 characters |
| Display name | 30 characters |
| Bio | 500 characters |
| Profile fields | 4 fields, 255 characters each |
| Poll options | 25 characters per option |
Instance-configurable limits
Unlike other platforms, Mastodon’s character limit depends on the instance you use. Some popular instances and their limits:
| Instance | Character limit |
|---|---|
| mastodon.social | 500 |
| mastodon.online | 500 |
| fosstodon.org | 500 |
| infosec.exchange | 500 |
Most instances keep the default 500-character limit, but instance admins can increase it. BulkPublish uses the standard 500-character limit.
How Mastodon compares to other text platforms
| Platform | Character limit |
|---|---|
| Mastodon | 500 (default) |
| Threads | 500 |
| Bluesky | 300 |
| X (Twitter) | 280 |
Mastodon gives you the same space as Threads and nearly double what X offers.
Tips for Mastodon posts
- Use content warnings generously — Mastodon culture values CWs for sensitive topics, spoilers, and even long posts
- Add image descriptions — the community strongly values accessibility and alt text
- Use hashtags thoughtfully — Mastodon search relies heavily on hashtags since full-text search is limited
- Engage authentically — the Fediverse favors genuine conversation over viral content
- Respect instance norms — each instance has its own community guidelines
Character limit in BulkPublish
BulkPublish enforces the standard 500-character limit for Mastodon posts. When composing threads, each part is tracked at 500 characters individually. You can also set post visibility (public, unlisted, or followers-only) when publishing.