You created a hashtag on Mastodon and expected it to appear in the trending section, but it never shows up. Mastodon uses a strict algorithm to determine which hashtags trend, and many user-created tags fail to meet the required thresholds. This article explains the exact reasons why a hashtag does not count toward trending, covering instance-level settings, account restrictions, and content moderation rules. By understanding these causes, you can adjust your posting strategy to improve the chances of your hashtag being promoted.
Key Takeaways: Why Mastodon Hashtags Fail to Trend
- Trending threshold: A hashtag must be used by at least 10 unique accounts within a rolling 24-hour window to be considered for trending.
- Moderation review: Server admins manually approve or reject each trending hashtag through the moderation interface.
- Account visibility: Posts from accounts that are private, silenced, or suspended do not contribute to the trending count.
Why Mastodon Filters Hashtags Before Trending
Mastodon does not automatically promote every hashtag that receives activity. The trending system is designed to prevent spam, abuse, and low-quality content from dominating the local or federated timeline. Each instance runs its own trending algorithm, which means the same hashtag can trend on one server but not on another. The algorithm evaluates three main criteria: usage volume, account diversity, and content compliance.
Usage volume is the raw count of posts containing the hashtag within the last 24 hours. However, the system does not simply count total posts. It requires a minimum number of unique accounts using the tag. This prevents a single user from inflating a hashtag by posting dozens of times. Account diversity is the second filter. If most uses come from accounts on the same server, the tag may still be rejected to avoid local echo chambers. Content compliance is the final gate. Posts that contain banned words, link to blocked domains, or violate the server’s content policy are excluded from the trending tally.
Moderation adds a human layer on top of the automated checks. Instance administrators can manually remove any hashtag from the trending list, even if it meets all technical requirements. This is common for tags related to sensitive topics, ongoing disputes, or commercial promotions that the admin considers inappropriate for the community.
Steps to Diagnose Why a Hashtag Is Not Trending
If your hashtag is not appearing in trending, follow these steps to identify the specific cause. You will need access to the Mastodon web interface and, in some cases, the moderation panel if you are an admin.
- Check the trending hashtag list on your instance
Open your instance homepage and look for the “Trending hashtags” section in the sidebar or under the Explore tab. If your hashtag is not there, click “Show more” to see all currently trending tags. This confirms the tag is absent from the local list. - Search for the hashtag directly
Type the hashtag into the search bar and press Enter. On the hashtag page, look for a label that says “Trending” or “Not trending.” If you see a crossed-out icon or the phrase “This hashtag is not trending,” the system has explicitly rejected it. - Count unique accounts using the tag
Scroll through the recent posts using the hashtag. Note the usernames of each author. Mastodon requires at least 10 unique accounts within 24 hours. If you see fewer than 10 distinct accounts, that is the reason. Check the timestamps to ensure all posts fall within the last day. - Review account visibility settings
Open the profile of each account that posted with the hashtag. Look for the lock icon next to the username. Locked accounts (private profiles) do not count toward trending. Also check if the account is silenced or suspended by your admin. These accounts are excluded entirely. - Examine post content for violations
Read each post containing the hashtag. Mastodon automatically filters posts that contain links to domains on the instance blocklist. Posts with Content Warnings that hide sensitive material may also be deprioritized. If any post violates the server rules, that post’s usage is removed from the trending count. - Ask the admin to verify moderation logs
If you are not an admin, contact your instance administrator and ask them to check the moderation panel. They can see if the hashtag was manually rejected or if it was removed after being approved. Admins can also review the “Trending hashtags” section in the admin dashboard and see the reason each tag was blocked.
If the Hashtag Still Does Not Appear After Meeting the Threshold
Hashtag manually removed by admin after approval
Even if your hashtag meets all automated criteria, an admin may delete it from the trending list manually. This action is logged in the moderation audit log. To check, go to Preferences > Moderation > Audit log and filter by “Trending hashtag.” If you see an entry with the action “removed” next to your tag, the admin decided it was not suitable. Common reasons include the tag promoting a product, containing a slur, or being part of a coordinated campaign. The admin may also remove a tag that is trending but not relevant to the instance community. There is no way to appeal this decision unless the admin changes their mind.
Hashtag blocked by instance domain or content filter
Mastodon instances maintain a list of blocked domains. If any post using the hashtag contains a link to a blocked domain, that post is excluded from the trending calculation. Additionally, the instance may have a custom keyword filter that automatically rejects posts containing certain words. To test this, create a test post with the hashtag and no other content. If the test post appears on the public timeline but the hashtag still does not trend, the filter is likely targeting the hashtag itself or a common word within it. Contact the admin to check the “Trending hashtags” settings under Preferences > Moderation > Trending hashtags. There, they can see if the tag is explicitly banned.
Account age or reputation threshold not met
Some instances configure additional rules for trending. For example, an admin may set a minimum account age of 30 days before a user’s posts count toward trending. This is not visible to end users. If your account is new, ask the admin to confirm whether such a rule exists. Similarly, accounts that have been reported multiple times may have their posts excluded from trending even if the account is not suspended. Check your account status by going to Preferences > Account > View profile and looking for any warning banners. If you see a message that your account is “limited” or “under review,” your posts will not contribute to trending.
| Item | Automated Filter | Moderation Action |
|---|---|---|
| Trigger | Less than 10 unique accounts in 24 hours | Admin manually removes the tag |
| Detection | Algorithm checks account diversity and post timestamps | Admin reviews the tag in the moderation panel |
| Resolution | Wait for more unique accounts to post with the tag | Contact the admin to request reinstatement |
You can now identify the exact reason why a hashtag is not trending on your Mastodon instance. Start by verifying the unique account count and checking for any moderation blocks. If the issue is automated, encourage more people from different servers to use the tag. If the admin removed the tag, respect the community guidelines and choose a different topic. For deeper control, instance administrators can adjust the trending threshold in the server configuration file under config/settings.yml by modifying the trending_threshold value.