No platform shares its full formula, but each has said what it looks for. Here's what they say, in their own words where we have them.
- The top three signals (Mosseri, Jan 2025): "The top three signals that matter most for ranking are watch time, likes and sends."
- Likes per reach matter more for reaching your followers.
- Sends per reach (DM shares) matter more for reaching non-followers.
- For Reels, Instagram predicts "how likely you are to reshare a reel, watch a reel all the way through, like it, and go to the audio page" (Instagram Ranking Explained).
- Shown less: low-resolution, watermarked, muted, bordered or mostly-text Reels, and reposted content.
TikTok
- The main signals are your interactions (likes, shares, comments, follows, what you watch to the end), then video info (captions, sounds, hashtags), then device and account settings, which are weighted lower.
- Finishing a longer video is a "strong indicator of interest".
- Followers: "Neither follower count nor whether the account has had previous high-performing videos are direct factors."
YouTube (including Shorts)
- Recommendations use viewing behaviour, likes, dislikes, subscriptions and feedback, including satisfaction surveys, plus channel reputation and quality.
- Shorts metric to watch: engaged views, meaning people who kept watching past the first moment (see article 20).
What it adds up to
- Hook in the first 1–3 seconds.
- Make something people want to send to a friend.
- Make it original.
- Upload a clean, high-quality file.