PostEaseThe short answer
A hashtag is a word or phrase written after a # sign, such as #SmallBusinessTips, that labels what a post is about so people browsing or searching that topic can find it. Platforms turn it into a link to other posts with the same tag.
Hashtags now work as labels, not as a reach trick, and most platforms limit them: Instagram allows up to 5 per post, Threads one topic tag, and YouTube ignores every hashtag on a video that has more than 60. Platforms also read the caption itself, so the words you write often do the same job.
Hashtag rules on each platform
What each platform says, in its own documentation, as set out in this blog’s hashtag strategy post:
| Platform | Rule |
|---|---|
| Up to 5 hashtags per post | |
| YouTube | Up to 3 shown above the title; more than 60 and all are ignored; unrelated tags can lead to removal |
| TikTok | Hashtags are part of the information TikTok uses to place a video |
| Threads | One topic tag per post, up to 50 characters, per Meta’s Threads API |
| Bluesky | Tags in text, plus up to 8 hidden tags; many custom feeds select by tag |
| LinkedIn and X | No limit found in the platforms’ own documentation |
Writing a hashtag people can read
A tag is read by people and by screen readers as well as by the platform:
| Habit | Example or reason |
|---|---|
| Capitalise each word (camel case) | #SocialMediaTips rather than #socialmediatips, so screen readers pronounce it as words |
| Put tags at the end | Put hashtags at the end of a caption rather than in the middle of a sentence |
| Be specific | Choose the five most specific to the post |
Hashtags and keywords
Platforms now read the whole post, not only its tags. TikTok says it uses captions, sounds and hashtags as information about a video, and Buffer’s TikTok algorithm guide suggests putting two or three keywords in the caption, the video details and the text on screen. Instagram ranks on what it predicts people will do with a post, such as reshare, watch to the end or comment, not on the tags. So write the caption in the words your audience searches, and let a few hashtags confirm the topic.
Do hashtags still help?
Modestly, and not always in the direction people expect. In Metricool’s 2026 study of 799,718 YouTube videos, Shorts with hashtags got about 10% fewer views but nearly 9% higher engagement. A tag helps the right people find a post; it does not make a weak post travel.
Questions
How many hashtags should I use?
Within each platform’s rule: up to 5 on Instagram, one topic tag on Threads, two or three on a YouTube video, and a few specific ones on TikTok. Fewer, more specific tags beat a long list.
Why should hashtags use camel case?
Capitalising each word, as in #SocialMediaTips, lets screen readers pronounce the tag as separate words, and makes it easier for everyone to read.
Do hashtags increase reach?
Not reliably. Metricool’s 2026 YouTube study found Shorts with hashtags got about 10% fewer views but nearly 9% higher engagement. Hashtags help the right people find a post rather than adding reach on their own.
Sources
- Instagram, Use hashtags on Instagram, checked October 2026.
- YouTube, Use hashtags for YouTube videos, checked October 2026.
- Meta, Threads Posts, Threads API documentation, checked October 2026.
- Metricool, YouTube trends 2026: what 799,718 videos tell us about views, Shorts, and watch time, July 2026.
- Buffer, TikTok algorithm guide, December 2025.
- TikTok, How TikTok recommends videos #ForYou, June 2020.