How the Instagram and TikTok algorithms work
There’s a lot of confident advice about “the algorithm” and very little of it is sourced. This guide sticks to what Instagram and TikTok have said publicly, then turns it into practical steps.
Updated October 2026
The short answer: Neither platform runs one simple algorithm. Instagram has said it uses several ranking systems for Feed, Stories, Reels and Explore, and has named watch time, likes and sends as major signals. TikTok says its For You feed weighs how people interact with videos, video information and device or account settings, and that follower count isn’t a direct factor. Bought followers or views don’t make either system favor you.
A note on sources
Both platforms keep the details of their ranking systems private, change them often and test variations on different users at the same time. What they have done is publish general explanations: Instagram through its head, Adam Mosseri, in posts and videos over several years, and TikTok through its “How TikTok recommends videos” explanation. Everything below is based on those public statements, at the time of writing. Where we draw a conclusion of our own, we say so. If you come across a long, precise list of “ranking factors”, ask where it came from.
Instagram: several systems, not one
Instagram has said repeatedly that there is no single “Instagram algorithm”. Instead, it uses different ranking systems for different parts of the app, each built around how people use that part:
| Surface | Mostly shows | What Instagram has described it as trying to do |
|---|---|---|
| Feed | Accounts you follow, plus some recommendations | Show the posts from friends and accounts you follow that you’re most likely to care about |
| Stories | Accounts you follow | Order stories by how likely you are to want to see each account’s |
| Reels | Largely accounts you don’t follow | Recommend short videos you’re likely to find entertaining and watch |
| Explore | Largely accounts you don’t follow | Help you discover new accounts and posts related to your interests |
The signals Instagram has named
In its explanations, Instagram has grouped the inputs it uses into broad categories: your own activity (what you’ve liked, saved, shared or commented on), your history with the person posting, information about the post itself (such as how people are responding to it and when it was posted), and information about the person who posted it.
More specifically, Mosseri has said that three of the most important signals are watch time, likes and sends (shares by direct message), and has talked about likes and sends relative to how many people a post reached. In plain terms: of the people who saw this, how long did they stay, and how many liked it or passed it to someone? He has suggested sends are especially telling when it comes to reaching people who don’t already follow you.
Originality and eligibility
Instagram has also said it wants to favor original content in recommendations over reposts of other people’s work, and that accounts mainly reposting content may see fewer recommendations. Separately, content has to meet Instagram’s recommendation guidelines to be suggested to non-followers. The Account Status screen in the app shows, at the time of writing, whether your account’s content is currently eligible to be recommended. Our guide to bans and shadowbans covers how to check it.
TikTok: the For You feed
TikTok’s own explanation describes its For You feed as a recommendation system that ranks videos for each person based on a combination of factors. It names three groups:
- User interactions: the videos you like or share, accounts you follow, comments you post, content you create, and whether you watch a video all the way through. TikTok has singled out finishing a longer video as a strong indicator of interest.
- Video information: details such as captions, sounds and hashtags.
- Device and account settings: things like language preference, country setting and device type. TikTok has said these get lower weight than the other two, because people don’t actively choose them as preferences.
TikTok has also said, in the same explanation, that neither follower count nor whether an account has had previous high-performing videos is a direct factor in the recommendation system. It acknowledges that accounts with more followers are likely to get more views simply because they have more people who chose to follow them, but the system itself doesn’t rank a video higher because of the number on the profile.
TikTok has also described deliberately mixing in videos outside a person’s usual interests, so the feed doesn’t become repetitive, and avoiding showing people things they’ve already seen.
What the two systems have in common
Read side by side, the public explanations point the same way. Both platforms are mainly predicting what a specific viewer will do with a specific post: watch it, finish it, like it, share it, follow. The inputs are overwhelmingly about people’s behavior toward content, not about the size of the account that posted it.
That has a practical consequence, and this is our reading rather than a platform statement: each post gets judged largely on how its first viewers respond. A small account can get a large audience for one strong post, and a large account can get very little for a weak one.
Practical implications
- Earn the first few seconds. If watch time and completion matter, a slow opening costs you. Put the payoff, the question or the most striking image first.
- Make things worth sending. A tip someone wants to pass to a friend, a joke about a shared experience, a “you need to see this”. Sends are a signal Instagram has named, and shares appear in TikTok’s list.
- Be original. Your own footage, your own take. Reposting other people’s clips is the opposite of what Instagram has said it wants to recommend.
- Help the system understand the post. Clear captions, relevant on-screen text and fitting sounds or hashtags give TikTok the video information it says it uses. A few accurate tags beat a wall of broad ones. On Instagram, a caption can run to 2,200 characters, so there’s room to say what the post is about.
- Judge posts by the right numbers. Look at average watch time, completion, shares and saves, not just likes. The engagement rate guide explains how to measure per view and per reach.
- Stay eligible. Check Account Status on Instagram and Account status on TikTok if reach drops sharply across many posts at once.
What neither platform has said
We haven’t seen either platform say that a particular posting time, a specific number of hashtags, a fixed posting frequency or a follower milestone unlocks distribution. Some of those may correlate with results on a given account, mostly because posting when your audience is around means more early views. Treat them as things to test on your own numbers, not rules.
Do bought followers or views help with the algorithm?
No, and we sell them. Here’s why, from the platforms’ own explanations:
- TikTok says follower count isn’t a direct factor. So adding followers to a TikTok profile doesn’t, by TikTok’s own account, change how its system ranks your next video.
- The signals are about behavior. Watch time, finishing a video, liking, sending and following are things viewers choose to do. Followers from a package don’t watch or share your posts.
- A views package raises a counter. It changes the number shown on one video. It doesn’t create people who choose to watch, rewatch, share or follow, which is what both platforms say they are looking for.
- Both platforms remove fake engagement. Their rules discourage artificial growth, and some of any bought numbers are usually cleared out over time.
What a package can change is the first impression on a person who has already arrived at your profile or video. That’s a social-proof effect on humans, not a signal to a ranking system. Our honest breakdown is on does buying followers work?, and growing followers without buying is where the algorithm-relevant work lives.
Platforms change their systems without notice, and their public explanations are summaries, not full specifications. Check the dates on any advice you read, including this page.
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