How to write X hooks that stop the scroll

You open the composer with a good idea and write it the way you would say it to a friend: "So I just wanted to share a few thoughts on invoicing." The idea is fine. The first line is a warm up, and the reader scrolling past never reaches the second one. The first line is one part of writing great X posts.

Good X hooks fix that. A hook is the first line of a post, written so the right reader stops and reads on. This guide covers what a first line has to do, seven structures that do it, rewrites you can borrow, and a ten minute routine for your next draft. A thread's opener has its own job; our guide to the first post of a thread covers it.

What is a hook on X

A hook is not a trick and not a separate sentence you bolt on. It is the opening of the post you were already going to write, rewritten so that it earns the second line.

It is also a line, not a paragraph. The Kairo Post hook grader grades only the first line, up to the first line break, because that is what a reader meets first. If your opening is a long block, the whole block is the hook, and that is usually the problem.

Why the first line decides whether anyone reads on

People scan a feed before they read any of it. The best evidence we found is a web usability finding, not an X statistic: Jakob Nielsen reported in 2009 that users typically see about 2 words of each item when they scan a list, and a little more if the lead words are short.

A timeline is a list of openings. We have no reason to think readers treat it differently, but treat the number as a direction, not a law.

For writing, we plan around the first five words. That is our working window, and the same window the hook grader scores. It is a bit more generous than Nielsen's 2 words and it works as a test: if the first five words carry no number, name, contrast or promise, the line is relying on the reader to be patient.

Nielsen Norman Group calls the same idea the inverted pyramid: put the most important information first, so the reader gets the point however little they read. A hook is that rule applied to one line.

The three jobs of a good hook

A strong first line does three things in a few words. It tells the right reader the post is for them, it gives one detail worth believing, and it leaves out the one thing the rest of the post supplies.

• Who it is for. The reader decides in a glance whether this is theirs. "Freelance designers:" does it. So does "Our checkout went down" for anyone who runs one.
• Why believe it. A number, a name, a time or a place. Nielsen Norman Group's headline advice is to be specific and give concrete information, not broad claims.
• What is missing. A gap the post closes. In George Loewenstein's information gap theory, curiosity comes from noticing a gap in what you know.

The third job is the one people skip. A line that states everything has no gap, and nothing pulls the reader down. A line that states nothing has a gap with nothing to hold onto. A summary of Loewenstein's paper notes that curiosity depends on existing knowledge, so the gap has to be about something your reader half knows.

That is why "Freelance designers: I lost $4,000 to one missing line in a contract" works as a shape. Every designer knows what a contract is. Nobody knows which line, yet.

Seven X hook structures and when each one works

Seven shapes cover most hooks. Choose by what you actually have, not by what is fashionable this month. All examples here are invented.

The first three lead with a fact.

The next four lead with a person or a point of view.

Not sure which one to pick? Start from what you have.

The hook grader has a library of templates for launches, lessons, contrarian takes, data, stories and how to posts. Copy a template, replace every bracket with a true detail, then grade it.

Hook examples: weak first lines and their rewrites

Each rewrite below keeps the facts and changes only the opening. The product, Fernwick, is made up, and so is every number. The grades are from the hook grader as it works on 1 October 2026.

Here is how that rewrite looks as a post, with the rest of the announcement underneath. The hook sets up the problem, and the body pays it off straight away.

The second pair is a lesson post. The weak version is an opinion with no evidence behind it.

The third pair is a how to post, where the weak line promises a list and the rewrite promises a size.

Notice what did not change. Fernwick is still the same product, the lesson is the same lesson, and the email advice is still email advice. A rewrite moves the strongest detail to the front. It does not add new claims.

How to rewrite a first line, one edit at a time

Many weak hooks improve in a few edits, and each edit fixes one thing. Here is one invented line taken from a grade F to a grade A in three edits, with the score the hook grader gave at every step.

Here is what moved at each edit, using the three rules that changed.

The middle edit is the useful one. Swapping "tips" for a real detail lifts specificity from 15 to 90, but tension drops from 65 to 20, because "tips" was doing a small amount of promising. The line only reaches an A when the third edit puts a turn back: "but one missing line was why".

In rewrites like this, one edit repairs a weakness and exposes the next.

The first edit is the easiest to make and the easiest to skip: cut everything before the first detail.

How to write a hook in 10 minutes

Write the post first and the hook last. You cannot open a gap before you know what fills it.

1. Write the post, then find the one detail

   Find the number, name, scene or cost that only you have. It is usually already in the draft, in the third or fourth sentence.

2. Write the line three ways

   Use three different structures from the cards above. Do not judge them yet. The aim is to see how different the same fact can sound.

3. Cut the warm up

   Delete everything before the first detail. Words like "just", "really" and "I think" add length and push the interesting part further away.

4. Check the first five words

   Is there a number, a name, a contrast or a promise in them? If not, move one forward.

5. Grade it, then read it aloud

   Paste the line into the hook grader, open the weakest rule and fix that one only. Then say the line out loud. If you would not say it to a colleague, rewrite it.

6. Check the payoff

   Read the line, then the second line. Does the second line answer what the first one opened? If it does not, the hook promises something the post does not give.

Kairo Post can help when you want several openings to compare. You can ask the AI Agent for a stronger hook while the facts stay the same, then pick one. Nothing publishes without your approval. The AI Agent page shows how.

Hooks that promise too much, and other mistakes we see

A hook is only as good as the post under it. When the line opens a gap and the post closes it, the reader gets what they were promised. When the post does not, they leave, and they remember.

Nielsen Norman Group makes the same point about headlines: write them so they make sense out of context, and choose clarity over hype or clever wording. We think a reader let down by one teaser has less patience for the next.

These are the mistakes we see most often:

• The warm up. "So I wanted to share" spends the first five words, the ones most readers see, on nothing.
• The announcement voice. "Excited to announce" tells the reader how you feel. They want to know what changed for them.
• The vague promise. "Some tips" has no number, no cost and no reader.
• The unpaid hook. The line opens a gap the post never closes.
• The borrowed template. The brackets are filled with vague words, so the line sounds like everyone else's.
• The same shape every time. A number and a colon on every post turns a pattern into a habit your followers notice.
• The link in line one. It costs 23 characters and gives a scanning reader nothing.

What a hook score can and cannot tell you

The hook grader is a checklist written as code. It scores six rules from 0 to 100 and weights them into a total, with 90 and above an A, 80 a B, 70 a C and 60 a D.

That makes it good at catching weak lines. It also means it can be wrong in both directions, and you should know where.

The grader cannot judge truth, and it cannot judge fit. It also does not know your audience, your topic or your timing. We have no data that says a B outperforms a C on X, so we do not claim it. Use the grade to find the weak rule, then use your judgement on the rest.

Before you post: a hook checklist

Run this on the first line of every post. It takes under a minute once you have done it a few times.

Draft a hook, grade it in the hook grader, fix the weakest rule, then check the full post with the AI phrase checker to catch the stock phrases that sneak into the body. When you are ready to publish, count the final post in the character counter, link and all.