Hashtag research is the process of finding tags that match your topic, your audience and each platform's rules, then testing them against real results. Start with what your audience searches for, check what each tag actually surfaces, keep a small set per topic, and respect platform limits, which differ widely in 2026.
Key takeaways
- Good hashtag research starts with relevance: a tag should describe the post's topic, audience or community, not simply be popular.
- Platform rules differ, from Instagram's in-app limit of 5 to Threads' single topic tag, so one hashtag list cannot be pasted everywhere.
- Look at what a tag shows you before you use it, including recent posts, the kind of accounts using it and whether it fits your content.
- Saved hashtag groups per topic make consistent, reviewable tagging fast, and a monthly review keeps them from going stale.
What hashtag research involves
Hashtag research means checking which tags are relevant, which are active and which are specific enough to be useful. A hashtag is a word or phrase prefixed with # that makes a post discoverable around a topic. Its value depends on the platform, which uses it for search, topic pages, categorisation or little at all.
Three questions guide the work. Is the tag clearly about this topic? Do people who care about the topic actually follow or search it? Can your post stand out in the content it sits beside? A tag that is huge and generic may bury you. A tag that is tiny may reach almost nobody. Most useful lists mix both ends with a few focused middle-sized tags.
No tag guarantees reach. Platforms rank content by many signals, and hashtags are only one of them. Treat hashtag research as a way to improve relevance, then let your own results decide what stays.
A step-by-step hashtag research process
Run this once per content pillar, not once per post.
- List your topics. Write three to five themes you post about, plus the audiences you want to reach. A bakery might list sourdough, local events and baking tips.
- Brainstorm seed tags. Use the words your audience uses. Check comments, search suggestions, competitor posts and community discussions for natural phrasing.
- Search each tag on the platform. Look at recent posts. Are they about your topic? Are they spammy, off-topic or dominated by big accounts? Discard tags that mislead.
- Look for variants. Singular versus plural, spelling differences and branded versus generic tags can behave differently. Note which ones attract the kind of content you want to be next to.
- Sort into three tiers. Broad topic tags, niche tags and community or location tags. Pick a few from each tier for each topic.
- Check for problems. Some tags are associated with spam or unrelated content, or have double meanings. A quick look at recent posts usually shows it.
- Save the set and record the date. Keep your list as a named group so you can reuse and review it.
Use a hashtag generator only for brainstorming. Suggestions from any tool still need the checks in steps 3, 4 and 6.
Platform hashtag rules to know
Rules vary, and they can change. The points below reflect published platform guidance at the time of writing.
Instagram's Help Center states that a post can have up to 5 hashtags. Instagram's developer documentation still lists 30 for API publishing, but the 5-tag limit is the in-app rule, so plan around 5. Place hashtags in the caption or the first comment, and choose tags that describe the post specifically.
Threads
Threads supports one topic tag per post, and a post can carry up to 500 characters. Because there is only one slot, pick the tag that best describes the conversation you want to join, not a string of keywords.
LinkedIn has no official hashtag limit. Three to five relevant tags is common advice but not a rule. Posts can run up to 3,000 characters, and tags usually work best at the end where they do not interrupt reading.
TikTok
On TikTok, hashtags and mentions are part of the caption, which can be up to 2,200 UTF-16 characters. Every tag consumes space you could use to describe the video.
YouTube
YouTube treats hashtags (the # words in a title or description) differently from hidden tags. If a video has more than 60 hashtags, YouTube ignores all of them. Use a few focused hashtags, and do not confuse them with the keyword tags in the upload settings.
Facebook and X
Facebook has no official hashtag limit, though a small number of relevant tags usually reads better than a long list. For X, keep tags minimal, since the 280-character limit leaves little room.
Build reusable hashtag groups
A hashtag group is a saved set of tags for one topic or content pillar. Groups save time, reduce typos and make it easier to see what you use.
- Name groups by topic and platform, such as "Sourdough tips - Instagram."
- Keep each group small, within the lowest limit you post to. Add platform-specific extras separately.
- Rotate tags across posts instead of pasting the identical block every time. Repeating exactly the same set on every post can look like automation.
- Keep a short "do not use" list with tags that attracted spam or off-topic content.
- Add the date of your last review to each group.
Schedule a monthly check. Look at which posts did well, scan the tags' recent content again and swap out any that drifted.
Measure and refine
Testing tells you more than guessing does. Compare similar posts with different tag sets, and keep everything else the same where you can. Look at reach from hashtags and non-follower reach in each platform's analytics, where available, and keep notes.
Do not read too much into small samples. A single post is noisy, so look for patterns across several weeks. If a tag consistently brings the wrong audience, remove it even if the numbers look decent. And if hashtags make no visible difference on a platform, spend that effort on the first line of your caption and the media.
Frequently asked questions
How do I find the right hashtags for my posts?
Start from your topics and your audience's own words, search each candidate tag on the platform, and check whether recent posts match your content. Then keep a small mix of broad, niche and community tags.
How many hashtags should I use on Instagram?
Instagram's Help Center states up to 5 hashtags per post as of 2026. Use tags that describe the post accurately instead of filling the limit.
Are hashtags the same on every platform?
No. Instagram has an in-app limit of 5, Threads supports one topic tag, YouTube ignores all hashtags on a video with more than 60, and LinkedIn has no official limit. Tailor the set for each platform.
Should I copy the hashtags my competitors use?
Use them as research, not as a template. Check whether a tag fits your content and audience first, because a competitor's tags may suit their products or location, not yours.
How MultiPost Studio helps
MultiPost Studio lets you save hashtag groups and insert them from the composer, with an option to shuffle a subset and to move hashtags to the first comment. Platform-aware validation shows each channel's hashtag limit and flags posts that exceed it before you publish. The hashtag generator is a quick starting point for brainstorming.