How the Instagram and TikTok algorithms work

The short answer

Nobody outside Instagram and TikTok knows exactly how their ranking works, and anyone who claims to is guessing. This guide sticks to what the two companies have said publicly, paraphrased and hedged, and is clear about where that runs out. Both platforms change their systems often, so treat it as a description of what they’ve said so far, not a rulebook.

Instagram: several systems, not one

Adam Mosseri, who runs Instagram, has explained more than once that there isn’t one “algorithm” deciding what everybody sees. Each part of the app has its own process, because people use each part differently:

• Feed and Stories are mostly made up of accounts you already follow, so ranking there is largely about which of those accounts’ posts to show you first.
• Explore is mainly for discovering accounts you don’t follow yet.
• Reels is mainly entertainment from accounts you don’t follow, so it leans heavily on what Instagram thinks you’ll enjoy watching.

This matters because advice that holds for one surface can be wrong for another. Getting more of your followers to see a carousel in Feed is a different problem from getting a Reel in front of strangers.

The signals Instagram has named

Instagram has grouped the inputs it uses into a few broad kinds of signal. In paraphrase:

• Your activity: what you’ve liked, shared, saved and commented on, and what you’ve watched.
• Information about the post: how popular it is, how quickly people are reacting, when it was posted and, for videos, how long it is.
• Information about the person who posted: for example, how many people have interacted with them recently.
• Your history with them: whether you comment on each other’s posts, message each other and so on.

From these, Instagram has said it makes predictions about how likely you are to do certain things with a post, such as spend time on it, comment, like, share or tap through to the profile, and ranks by those predictions.

Sends and shares

More recently, Mosseri has picked out watch time, likes and sends (people sharing a post in a direct message) as among the most important signals. He has described sends as carrying particular weight for reaching people who don’t already follow you, with likes mattering more among your existing followers. If you want reach beyond your own audience, a post people forward to a friend is the clearest thing Instagram has pointed to.

Originality

Instagram has said it wants to favour original content over reposts. It has described changes in which accounts that mainly repost other people’s videos, sometimes called aggregators, can be replaced in recommendations by the original creator, and in which accounts that repeatedly post content they didn’t make may stop being recommended. Reposting someone else’s viral clip as your own is, by Instagram’s account, the opposite of what it says it rewards.

Account Status and being recommendable

Showing up in Explore, Reels or suggested posts for non-followers is something Instagram treats as a privilege rather than a right. It publishes recommendation guidelines describing content it may not recommend, even when that content is allowed on the platform. Under Account Status in settings, you can see whether any of your content has been removed and whether your account is currently eligible to be recommended to people who don’t follow you. This is the most direct, official answer to “am I being held back?”, and it’s worth checking before you assume anything. Our guide on bans and shadowbans goes into this in more detail.

Trial Reels

Instagram has introduced Trial Reels for professional accounts. A Trial Reel is shown first to people who don’t follow you, not to your followers, so you can see how it performs with strangers before deciding whether to share it with your own audience. It’s a useful way to test a new style or topic without it appearing in your followers’ feeds if it flops.

TikTok: the For You feed

TikTok set out its approach in a newsroom explainer titled “How TikTok recommends videos #ForYou”, and has repeated the main points in its help pages since. In summary, recommendations are based on a mix of factors:

• User interactions: the videos you like or share, accounts you follow, comments you post, content you create, and how you watch, including whether you finish a video.
• Video information: things like the caption, the sound and any hashtags.
• Device and account settings: for example your language preference, the country you’ve set and the kind of device. TikTok has said these get less weight than the others, because people don’t actively choose them as preferences.

TikTok has also said that each factor is weighted by how strong a signal it is. Watching a longer video all the way through, for instance, says more about your interest than where you happen to live.

Followers aren’t a direct factor

The point most relevant to anyone thinking about their numbers: TikTok has said that neither follower count nor whether an account has had high-performing videos before is a direct factor in the recommendation system. Accounts with more followers do tend to get more views, because more people follow them, but a video from a new account can be recommended on its own merits. TikTok has also said it tries to mix things up, so you generally won’t see two videos in a row from the same creator or with the same sound.

Videos that won’t go on For You

TikTok’s community guidelines include standards for what is eligible for the For You feed. Some content stays on the platform but isn’t recommended. Broadly, that covers things TikTok considers unsuitable for a general audience and things it considers low-quality or unoriginal, such as straight reuploads of other people’s content or misleading material. As with Instagram, being allowed on the app and being recommended by it are two separate bars.

What this means in practice

1. Make something people send. On Instagram, a post that gets shared in direct messages is the clearest route Mosseri has pointed to for reaching non-followers. A Brighton café’s “five places to sit outside in winter” is more sendable than a photo of a flat white.
2. Hold attention early. Both companies have mentioned watch time or completion. Open with the payoff and keep videos as long as the idea needs, no longer.
3. Post your own work. Reposting clips you didn’t make is what both platforms say they’re moving away from recommending.
4. Write captions that say what the video is. Captions are part of the video information TikTok has named, and plain words help both apps understand a post.
5. Test on strangers. Instagram’s Trial Reels let you try a format on non-followers first; on TikTok every video gets its own chance anyway.
6. Check eligibility before blaming the algorithm. Instagram’s Account Status shows whether you can be recommended; read TikTok’s For You eligibility standards if a run of videos stalls.

For the day-to-day habits of growing an audience, see how to grow followers organically. To see whether changes are working, track your rate with the method in engagement rate explained.

Myths worth dropping

“There’s a perfect time to post”

Mosseri has said posting time matters less than people think. Posting when your followers tend to be online may help a post get its first reactions sooner, but there’s no time slot that unlocks reach on its own, and recommendations to non-followers can keep going for days.

“More hashtags, more reach”

Mosseri has said hashtags aren’t a major driver of views and work mainly as a way of labelling what a post is about. Instagram has announced a cap of five hashtags per post, which is rolling out. A handful of accurate tags is plenty; thirty generic ones won’t help.

“One flop and your account is finished”

TikTok has said previous high-performing videos aren’t a direct factor in recommendations, which also suggests a weak one isn’t a permanent mark against you. Each video is assessed by how people respond to it.

“Big follower counts get pushed to more people”

Not according to TikTok, and on Instagram the signals it describes are about how people interact with posts. Followers help because they’re people who might see and react, not because the number itself unlocks anything.

Where buying followers fits, honestly

Given the above, it’s worth being plain about what a follower package does and doesn’t do. Bought followers don’t like, comment, share, save or watch, so they don’t produce any of the positive signals either platform describes. On TikTok, follower count isn’t a direct recommendation factor at all, so a package won’t push your videos to new viewers. On Instagram, the systems that show posts to strangers run on predicted interaction, which bought followers don’t supply. Neither platform has published how it treats followers who never interact, so we won’t claim that they help or that they harm ranking.

What a package can change is the first impression for a real person landing on your profile: a café with 2,000 followers looks more established than one with 40. That’s a judgement about people, not about the algorithm. It also comes with a cost to your follower-based engagement rate, which the engagement rate guide works through with numbers, and both platforms remove accounts they consider inauthentic, which is why our orders include a 30-day refill. If you want the trade-offs in one place, read does buying followers work? before you choose.