What counts toward the Mastodon limit
500 characters is Mastodon’s default, but each server sets its own limit. If you post from a server other than mastodon.social, check its limit first; the server’s instance information (/api/v2/instance) lists it.
Mastodon also counts two things differently from this counter. Every link counts as 23 characters however long it is, so a long URL costs less than it looks and a short one costs more. And for a mention, only the username counts, not the server after it: @name@example.social counts as @name. Adjust for both when you’re near the limit.
Example: 450 characters of text, a space and an 80-character link show as 531 here, but Mastodon counts 450 + 1 + 23 = 474, so the post fits.
Mastodon character limits
| Field | Limit (characters) | Notes |
|---|---|---|
| Post | 500 | Default. Each server can change it. |
| Bio | 500 | |
| Display name | 40 | |
| Username | 30 | |
| Poll option | 50 | On mastodon.social, up to 4 options. |
Hashtags on Mastodon
Hashtags let anyone searching for that tag find the post. They can contain letters, numbers and underscores, but can't be numbers only.
Tips for Mastodon posts
- Check your server’s limits, because admins can change them.
- Add a media description (alt text) to every attachment.
- Write multi-word hashtags in CamelCase, like #SocialMediaTips, so screen readers read them correctly.
- Use content warnings for spoilers and sensitive topics.
- Post full URLs rather than shorteners. Links count as 23 characters anyway.
Publish Mastodon posts that fit, on schedule
Postocial publishes to Mastodon on any instance. Write your Mastodon post next to the versions for other networks, break a longer idea into a thread, add a custom thumbnail to videos and schedule it.
On Premium and higher plans, replies come into the unified inbox. See how Postocial works with Mastodon.
Sources
The Mastodon limits on this page come from these pages. Researched on . Networks change their limits without notice, so check the official pages before a big launch.