Hashtags work on Threads, but only one per post. Threads calls them topic tags: a post takes one topic, the tagged text shows in blue, and tapping it opens search results for that topic. In a post published through the API, only the first valid # word becomes the topic. Meta says posts with a tagged topic generally get more views than posts without one, so one well-chosen tag is worth adding.
Key Takeaways
- One per post: the Threads Help Center allows up to 1 topic per post. Through the API, the first valid tag in the text becomes the post’s tag.
- What a tag does: tapping it shows search results for that topic. At launch, Mosseri put it as “the tag view is the search view”.
- Reach: Meta wrote in 2025 that, by its internal data, posts with tagged topics “generally receive more views”. It published no figure.
- App and API differ: in the app the # is optional and a tag holds spaces. In text published through the API, as scheduled posts are, a tag ends at the first space or punctuation mark.
- Numbers are not tags: #1 or #2026 stays a number sign, and Threads moves on to the next valid tag.
Threads topic tags at a glance
Every row comes from the Threads Help Center, Meta’s Threads API documentation or Meta’s announcements, read in November 2026. Where a rule is stated only for the API, the row says so.
| Question | Answer | Where Meta says it |
|---|---|---|
| Tags per post | 1 | Help Center; API documentation |
| Tag length | Up to 50 characters (1 to 50 through the API) | Help Center; API documentation |
| Is the # needed? | No in the app; yes for a tag typed into text sent through the API | Help Center; API documentation |
| Spaces in a tag | Allowed in the app; through the API, a space ends the tag | Help Center; API documentation |
| Several # words in one post | Only the first valid one becomes the topic (API) | API documentation |
| #1, #2026 | Not converted into a tag (API) | API documentation |
| Tapping the tag | Shows search results for that topic | Help Center |
| Effect on views | Tagged posts “generally receive more views” (Meta’s internal data) | Meta newsroom, 2025 |
Do hashtags work on Threads?
Yes, as topic tags, one per post. Tagging a topic, the Threads Help Center says, “allows others on Threads to discover your post and other posts associated with that topic in real time”, and tapping the tag shows search results for that topic. A second or third hashtag cannot add another topic, because only one topic attaches to a post.
That was a deliberate choice. When tags rolled out worldwide on 7 December 2023, Adam Mosseri, head of Instagram and Threads, listed the design: “No # marks, support for multiple words, only one tag per post, and the tag view is the search view.” The hope, he wrote, was to focus tags “more on communities and less on engagement hacking”.
Most pages that rank for this question are news from that launch week and still describe tags as “hashtags without the hash”. That part has changed. The Help Center now says a topic “doesn’t need to include the # symbol, but can if that is your preferred content strategy”, and that the # may add functionality on other platforms once Threads works with the fediverse, the network of apps such as Mastodon.
How are Threads topic tags different from hashtags?
A Threads tag labels the post with exactly one topic and ties it to that topic’s search results. On Instagram or X, a hashtag is a word in the caption and a post carries several. A Threads tag added in the app also holds spaces and special characters, so “Book Club” works as a topic as written.
Meta drew the comparison itself in its December 2023 announcement: tagging is much like using a hashtag on Instagram, except a Threads post takes one topic, and unlike a hashtag it allows spaces and some special characters. Instagram now allows five hashtags per post, as our guide to the Instagram hashtag limit explains.
Tags have since become the base of other features. Meta counted more than 50 million topic tags created by July 2024. Communities, tested since October 2025 on more than 100 popular topics, are built on topic tags and custom feeds, and a three-dot icon on a tag shows that its topic has a community to join.
What happens to a second hashtag on Threads?
It does not become a second topic. The Help Center allows “up to 1 topic per post”, and Meta’s API documentation says only one topic tag is allowed per post, “so the first valid tag included in a post of any type (text-only, image, video, carousel) via the API is treated as the tag for that post”. The word “valid” matters, because Threads skips some # words.
The same documentation sets what counts as valid in the text of a post:
- A valid tag starts with a hash sign and runs 1 to 50 characters.
- A whole number after the # is not converted, because Threads reads the # as “number”. “#1 tip” or “#2026” never becomes the topic; the next valid tag does.
- The tag ends just before a space, tab, line break, full stop, ampersand, @, exclamation mark, question mark, comma, semicolon or colon.
That last rule catches multi-word tags. In a post sent through the API, “#content marketing” tags only “content”, and “#R&D” tags only “R”. Write the topic as one word, such as #ContentMarketing, or use the Tag button in the app for a topic with spaces.
Order matters too. A post that opens with “#1 mistake” and ends with #Photography gets the topic Photography. One that opens with #Monday and ends with #Photography gets Monday. The other Threads limits are in our guide to the Threads character limit.
Do topic tags help reach on Threads?
Meta says they do, in general terms. Announcing profile topics in 2025, it wrote: “According to our internal data, posts with tagged topics generally receive more views than those without one, making them an effective way to help you reach more people.” Meta gave no figure and did not say whether the effect holds for every account or subject.
Treat that as an average across Threads, not a promise about your next post. One plausible reason is mechanical: a tagged post shows up when someone taps its topic, and an untagged post has no topic to show up under. The same announcement said Meta made the tag more prominent on posts in the For You feed and added composer prompts that suggest trending topics, or topics related to your earlier posts.
A tag does not rescue a weak post. Threads ranks its For You feed on its own terms, and readers in some countries steer it with Dear Algo and Your Algo, which our comparison of Threads and X describes. Nothing we read from Meta says a tag lowers reach, or that a post full of # words is treated as spam.
To see the effect on your own account, alternate tagged and untagged posts of the same kind for two or three weeks and compare views in Threads Insights. It will not prove anything, but it shows whether your audience finds you through topics.
How do you use hashtags on Threads?
Add one topic per post, ideally one people already search. In the app, tap Tag or type #, start typing, and pick from the existing or trending topics Threads suggests, or create your own. Place it where it reads naturally, since the tagged text shows in blue inside the post.
Four habits make the tag earn its place:
- Prefer an existing topic. Meta’s 2023 announcement says topics other people created appear as you type. An established topic has readers; a new one starts empty.
- Be specific. “Sourdough” reaches people who care about sourdough. “Food” drops the post into a crowd.
- Tag each post in a thread. A multi-post thread is published as separate posts, each a reply to the one before, and the one-topic limit is per post, so each can carry a topic. Give the first post the topic that sums up the thread.
- Clean up cross-posts. An Instagram caption with five hashtags, posted through the API, gives Threads one topic and four words of clutter. Keep the one that fits.
How does PostNext handle Threads topic tags?
PostNext publishes to Threads through Meta’s official API and sends your text as written, without filling the API’s separate topic field. So Threads applies its in-text rule: the first valid #tag in the post becomes the topic. Write the tag as one word with the # in front, and put it before any other # word.
The AI writers in the PostNext Threads scheduler work to the same rule: their Threads instructions say a post takes one topic tag, the first #tag in the text, and to use at most one or none. Every suggestion stays editable, and the AI does not read live Threads trends, so check the trending topics in the Threads composer when timing matters. Threads metrics are not in PostNext yet; compare tagged and untagged posts in Threads Insights. The free Threads post formatter counts the tags in a draft against a limit of one.
Other networks have moved in different directions. LinkedIn dropped hashtag following altogether, as our guide on whether hashtags still work on LinkedIn explains.
Frequently Asked Questions
Does Threads use hashtags?
Threads uses topic tags, which work like a single hashtag. Each post carries one topic of up to 50 characters, and tapping it shows search results for that topic. In the app the # sign is optional and a topic may include spaces.
How many hashtags can you use on Threads?
One. The Threads Help Center allows up to 1 topic per post. If a post published through the API contains several # words, Meta’s documentation says the first valid one becomes the tag for that post and the rest are not topics.
Do Threads topic tags increase reach?
Meta says posts with a tagged topic generally receive more views than posts without one, based on its internal data, but has published no figure. A tag helps people searching that topic find the post; it does not make a weak post rank well.
Why did my second hashtag not work on Threads?
Threads attaches only one topic to a post, so a later # word is not a topic. Through the API, a # followed by a whole number, such as #2026, is skipped, and a tag ends at a space or punctuation mark, so “#content marketing” tags only “content”.
Can a Threads tag have spaces?
Yes, when you add it in the Threads app, where the Help Center says a topic may contain spaces and other special characters. In text published through the Threads API, such as a scheduled post, a space ends the tag, so write a multi-word topic as one word.
Related reading
- Threads Character Limit: Posts, Attachments, Tags
- Instagram Hashtag Limit: Why It Is Now 5 Per Post
- Do Hashtags Work on LinkedIn in 2026?
- Threads vs X: Which One Should You Post On?
- Threads vs Bluesky: Which One Should You Post On?
Sources
- Threads Help Center, Tag a topic in your post on Threads (November 2026)
- Meta for Developers, Threads API: Posts, section “Topic Tags, Links, and GIFs”, updated 30 October 2026 (read November 2026)
- Meta for Developers, Keyword and Topic Tag Search (November 2026)
- Adam Mosseri on Threads, tags rolling out globally and the design note, 7 December 2023 (read November 2026)
- Meta Newsroom Japan, Threads introduces topic tags, 8 December 2023 (read November 2026)
- Meta Newsroom, New Threads Features for a More Personalized Experience That You Control, section dated 24 April 2025 (read November 2026)
- Meta Newsroom, India Is One Of The Most Active Countries for Threads Globally, 4 July 2024 (read November 2026)
- Meta Newsroom, Introducing Threads Communities, October 2025 (read November 2026)
- PostNext, postnext.io/threads-scheduler and postnext.io/tools/threads-post-formatter (November 2026)
