How to Write a YouTube Hook for the First 3 Seconds

Viewers decide whether to stay within the first few seconds. On Shorts it's a swipe, on long videos it's the back button, and either way the rest of your script never gets heard. This guide covers the hook formulas that work, the openings that reliably lose people, and how SceneGen's hook & retention check and Fix hook apply those rules to your own storyboard before you render.

Why the first 3 seconds decide the video

A viewer arrives with one question: is this the video the title promised? The opening line has to answer yes and add a reason to keep watching. Your audience retention graph in YouTube Studio shows the result as the steep drop at the start. A good hook flattens it. A greeting, a slow scene-setter or a long title card makes it steeper.

Four hook formulas that work

Each of these fits in one short sentence, ideally under about 15 words.

1. The question the video answers

"Why did the Roman Empire keep paying its enemies?" A real question opens a curiosity gap that only the video closes. Make it specific. "Have you ever wondered…" is a warm-up, not a question.

2. The bold claim

"The most dangerous animal in Australia isn't a spider." You state something surprising and then spend the video earning it. Only claim what the video actually supports.

3. The number and the stakes

"This mistake costs new investors about 2% a year, every year." A concrete number plus what the viewer stands to gain or lose makes the promise tangible. Use numbers the video really contains.

4. The flash-forward

Open with your strongest moment or line, then go back to explain how you got there. This works in any language and any niche.

Openings that lose viewers

• The greeting. "Hey guys, welcome back to the channel" tells the viewer nothing about the video.
• "In this video I will…" It announces content instead of delivering it.
• The scene-setter. "In the vast world of…" or "Once upon a time…" sets a mood but promises nothing yet.
• The long first sentence. Twenty-plus words take eight or more seconds to land.
• A title card before the hook. Seconds of branding that play before anyone hears a word.
• An early subscribe ask. Asking for the subscribe before you've delivered anything.

How SceneGen checks your hook (and the rest of the video)

Every project page has a Hook & retention check. It runs a set of fixed rules over your storyboard: each scene's narration, length, voice timing and visuals. No AI model is involved, so it takes milliseconds and you can run it before you render. It gives a Retention readiness score out of 100. That score is a heuristic, not a prediction of real audience retention, and the page labels it that way.

What it looks for:

• Hook: scene 1 with no narration, a greeting or a slow scene-setter in the first ~3 seconds, a first sentence with no question, number, stakes or bold claim, and first sentences over ~22 words.
• Stage directions read aloud: labels like "Narrator:" or "[music swells]" that would end up spoken.
• Pace: narration well outside roughly 140–170 words per minute.
• Dead air and visual holds: silence, or one image held on screen too long.
• Pattern interrupts: long stretches with nothing changing.
• Payoff: narration that never mentions what the title promises.
• Intro and CTA: a title card before the hook, a long first scene, a call to action before the payoff, or a Short that ends on a sign-off or an outro card.
• Captions: captions off on a Short, or a caption style too small for vertical video.

Each issue is tied to a scene with a one-line suggested fix, so you can jump to that scene in the Studio. The word lists are English-first. Other languages get the checks that don't depend on words, like pace, visuals, captions and structure. For videos you upload to YouTube through SceneGen, the page can also show the real audience-retention curve with scene boundaries under it. That part is optional: it needs you to connect YouTube Analytics, and it only appears once YouTube has enough views to report retention.

How to fix a weak hook in SceneGen, step by step

1. Open your project and read the Hook & retention check. Each suggestion is marked by importance and tied to a scene.
2. Click Fix hook. You instantly get ready-made openings for scene 1: a question, a bold claim, a number with its stakes, and a flash-forward. The number template only uses a number your script already says. It never invents one.
3. Optionally ask for an AI rewrite. It's one short call that runs only when it won't slow anyone's video down. When the AI is busy, you get the templates and a "try again in a few minutes" instead of a wait.
4. Preview each option, edit it, and accept the one that fits. Nothing changes in your project until you accept.
5. Re-run the check, then render. After upload, compare the real retention curve (if connected) against the scene where most viewers left.

Hooks and packaging work together

The hook has to deliver on the title and thumbnail. If the packaging promises one thing and the first line talks about another, viewers leave even when the line itself is strong. Build both together: a packaging pack for the click, and a hook that confirms it in three seconds. For script structure beyond the opening, read AI script writing for YouTube. For Shorts specifics, read how to make YouTube Shorts with AI.

Check your next hook

The hook & retention check is included on every project. Create a free video and run it on your first script, or see the full feature list.

Frequently asked questions

How long should a YouTube hook be?

Usually one sentence, under about 15 words, which is roughly the first 3–6 seconds of narration. SceneGen flags first sentences over about 22 words.

Is the retention readiness score my real retention?

No. It is a heuristic score from fixed rules over your storyboard. Real retention comes from YouTube Analytics. SceneGen can show that curve when you connect Analytics and the video has enough views.

Does Fix hook make up facts?

No. The templates only use numbers your script already contains, and the AI rewrite is instructed not to invent facts or numbers. You preview and edit every option before accepting it.

Does the hook check work in other languages?

Partly. The word-based checks are English-first. Other languages get the checks that don't depend on words: questions, real numbers, common greetings, pace, visuals, captions and structure.