The short version: Broad, plain-English hashtags (think #smallbusinesstips, #marketingtips, #contentcreator) work on both platforms, but the truth is hashtags carry far less weight on TikTok than the algorithm cares about watch time and completion rate. Copy-pasting the same ten tags across both apps is lazy, and it costs you reach on at least one of them.
The question everyone asks and nobody answers
I get this question at least once a week, usually from a small business owner who's been told to "just post the same reel everywhere with the same hashtags." I understand why. It feels efficient. You've already done the work of writing the caption, filming the clip, editing it. Why not just fire it out to both platforms with the same five or six hashtags and move on?
Because it doesn't work like that, and I've got the receipts to prove it.
Back in 2023, when I was rebuilding my presence after a rough few years, I ran a six week test across my own TikTok and Instagram accounts. Same 14 videos, posted to both platforms within an hour of each other, same hook, same edit. The only variable I changed was the hashtags. On half the videos I used identical tags on both platforms. On the other half I tailored them. The tailored batch got 34% more reach on Instagram and roughly the same on TikTok, which told me something a lot of "experts" won't say out loud: hashtags do more work on Instagram than they do on TikTok, and treating them as equal partners across the two apps is where most people waste their time.
What crosses over between the two apps
There is a shortlist of hashtag types that perform on both platforms, and it's smaller than people want it to be.
- Niche identity tags - things like #smallbusinessowner, #ukbusiness, #contentcreator, #marketingtips. These work because they describe who's watching, not what's trending. Both algorithms use them to categorise your account over time.
- Format tags - #dayinthelife, #behindthescenes, #howto, #storytime. These signal content type and both platforms' recommendation systems pick up on them for suggesting similar content to similar users.
- Broad topic tags with real search volume - #productivitytips, #businesstips, #ai2026. People type these into the search bar on both apps now, which matters more than it used to.
What doesn't cross over well: hyper trending TikTok sound-based tags (they mean nothing on Instagram), and Instagram's community hashtags built around specific hashtag challenges that TikTok's algorithm simply ignores. If you want the deeper breakdown of what moves the needle on TikTok specifically, I wrote a full piece on what hashtags get the most engagement on TikTok that goes into the mechanics platform by platform.
The uncomfortable bit about TikTok
Here's the part that annoys people. TikTok's own creators have said publicly, more than once, that hashtags are not a major ranking factor for the For You Page. Watch time, completion rate, shares and rewatches carry far more weight. I've had videos with zero hashtags outperform videos with fifteen, purely because the hook was stronger and people watched to the end.
So why do I still use hashtags on TikTok at all? Two reasons. First, they help with search, because more people are now using TikTok as a search engine the way they'd use Google. Second, they still help the algorithm bucket your content into a topic category, which matters for suggesting your videos to the right audience over time, just not as much as everyone claims.
On Instagram it's different. Reels and feed posts both still get meaningful discovery through hashtag search and the Explore tab, and Instagram has quietly rebuilt hashtag search into something closer to what it was in 2019, when hashtags were the main discovery tool on the platform. That history is worth knowing, and I covered how Instagram's whole promotion mechanics shifted in this piece on what works for reach on Instagram, which still holds up even though the platform has moved on since.
My actual step-by-step process
This is exactly what I do now for every piece of content that goes on both platforms, and it takes about six minutes per post once you've built your lists.
- Step 1: Write three hashtag lists in a spreadsheet, not from memory. One list of 10 broad niche tags, one list of 10 format tags, one list of 5 to 8 trending tags refreshed weekly.
- Step 2: Check what's trending right now rather than guessing. I use the TikTok Creative Center and Instagram's own search bar suggestions every Monday morning, and I've written up a free method for finding these without paying for a tool in how to find trending hashtags for free.
- Step 3: For TikTok, use 3 to 5 hashtags total. Two broad, one format, one trending, one niche. Don't stuff more in. It doesn't help and can look spammy.
- Step 4: For Instagram, use 8 to 12. Mix broad, niche, and a couple of long-tail tags with lower competition, because Instagram still rewards volume and specificity more than TikTok does.
- Step 5: Overlap by design, not accident. Keep 3 to 4 tags identical across both platforms (usually my niche and format tags), and let the rest differ.
- Step 6: Track it. I keep a simple note of reach per post for four weeks, then drop whatever tag consistently sits in the bottom third.
That fourth step is the one people skip. You cannot know what's working if you never look. I check mine every Sunday night with a cup of tea, it takes fifteen minutes for a week's worth of posts.
A concrete example from a client account
I worked with a travel content creator last year, small following, around 8,000 on Instagram and 12,000 on TikTok, who was using generic tags like #travel and #wanderlust on both, getting decent but flat numbers. We swapped her broad tags for destination-specific and format-specific ones, things like #scotlandtravel, #hiddengems, #solotravel2026 on Instagram, and kept TikTok stripped back to three tags focused on search intent like #scotlandtiktok. Within three weeks her Instagram reach on new posts was up 61%, TikTok stayed roughly flat but her watch time crept up because she'd also tightened her hooks in the same period. If you're in the travel space specifically, I go much deeper on this in the best hashtags for reaching new travel customers, which covers destination tags that convert into bookings rather than just views.
The lesson from that client wasn't really about hashtags at all, if I'm honest. It was that Instagram rewarded the specificity and TikTok rewarded the content quality change that happened at the same time. That's the trap with this whole topic. People want one tidy answer, "use these exact hashtags," when the real answer is that the two platforms weight the same signal completely differently.
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Hashtags that I'd avoid on both
A few categories consistently underperform on both platforms and I see people using them constantly.
- Massive generic tags like #love, #instagood, #viral, #fyp. Millions of posts a day means your content vanishes in seconds. #fyp specifically does nothing on TikTok, the platform has confirmed this repeatedly, it's a leftover habit from 2020.
- Follow-for-follow tags like #f4f, #likeforlike. These attract bots and engagement pods, not real audience, and both platforms actively suppress accounts that lean on them.
- Branded hashtags with no search volume unless you're running a specific campaign with a clear reason for people to use them, a made-up branded tag with three posts total is wasted space in your caption.
Where this fits with your wider strategy
Hashtags are one lever, not the whole machine. If you're building out a full content plan across platforms, it's worth remembering that YouTube Shorts now uses a completely different hashtag logic again, more tied to search and less to trending discovery, which I broke down in what hashtags perform best on YouTube. And if Facebook is part of your mix too, its hashtag system barely functions as discovery at all anymore, more detail on that in how Facebook hashtags work for reach. The wider point is that no single hashtag strategy survives contact with more than two platforms unchanged. Treat each one as its own small negotiation.
My honest advice after years of watching this shift: stop looking for the magic list of ten hashtags that works everywhere, because it doesn't exist and anyone selling it to you is guessing. Build your three lists, keep three or four tags consistent as your anchor, let the rest flex to the platform, and check your numbers weekly. That's it. That's the whole system, and it took me six weeks of testing to arrive at something this simple.
Frequently asked questions
Can I use the exact same hashtags on TikTok and Instagram?
You can, but you'll leave reach on the table on at least one platform. Keep 3 to 4 anchor hashtags identical across both, and tailor the rest to how each platform's search and discovery works, more tags on Instagram, fewer and more search-focused on TikTok.
How many hashtags should I use on Instagram versus TikTok?
Aim for 8 to 12 on Instagram, mixing broad, niche and long-tail tags. Keep TikTok to 3 to 5, since TikTok's algorithm weighs watch time and completion far more heavily than hashtags.
Do hashtags still matter on TikTok in 2026?
They matter for search and content categorisation, not as a major ranking factor. Videos with strong hooks and high completion rates regularly outperform videos with more hashtags but weaker openings.
What's the biggest mistake people make with cross-platform hashtags?
Copy-pasting one hashtag list to both platforms without checking performance. Each platform reads the same tag differently, and if you never track reach per post over a few weeks, you'll never know which tags are pulling their weight.
Sources worth reading
Related reading: How to Change a YouTube Thumbnail After Publishing and What Is the May 13 Date Shown on Instagram Reels?.
