The first 100 words decide who keeps reading
TL;DR
Above 100 words, the reader has committed and almost always finishes. Below it, every weak sentence costs you a percentage of the audience. Five factors drive a strong opening: a strong action verb in the first sentence, sentence-length variety, reader-centric framing (you/your), specificity (numbers, named things), and a hook signal (question, number, imperative).
Open rate is a vanity metric. Completion rate is the one that drives every downstream number - clicks, replies, conversions, retention. And completion rate is decided in the first 100 words. By word 101 the reader has either committed or closed the tab. That makes the opening the most leveraged 30 seconds of writing in the entire email.
The 100-word threshold
Why 100 words specifically? It is the empirical threshold above which the engagement curve flattens. Plot completion rate against word position and you see a steep drop-off in the first 80-100 words and a gentle decline after that. Readers who reach word 100 almost always reach word 500. Readers who quit before word 100 quit much earlier - usually around word 30-40.
The implication: the middle and end of your email are doing less work than you think. Spending another hour polishing the conclusion is rarely the highest-leverage move. Rewriting the first paragraph is.
The five hook factors
1. Strong action verb in the first sentence
The opening verb sets the energy. Strong: I deleted, We cut, You can save, Imagine, Picture. Weak: Today I want to, We hope, This is the email where, As you may know. A strong verb in the first sentence puts the reader in motion immediately.
2. Sentence-length variety
All sentences the same length is monotone. The pattern that holds attention: short, then medium, then short again. "Last Tuesday I deleted 80 percent of our marketing emails. Here is what happened next, what we kept, what we cut. The unsubscribe rate dropped." The reader reads the rhythm before they read the words.
3. Reader-centric framing
Count the you/your in the first 100 words. Zero is bad - the reader does not feel addressed. Three to five is good. Above seven feels performative. The shift is from "We launched a new feature" to "You can now skip the manual export step." Same content, different protagonist.
4. Specificity
Numbers and named things outperform vague claims by a wide margin. "Three trends emerged this quarter" beats "A few interesting things happened lately." "At Klaviyo, the migration" beats "At a leading email platform, a major change." Specificity signals authority and effort.
5. Hook signal in the first sentence
One of three patterns: a question ("What if your unsubscribe rate is the wrong metric?"), a number ("We cut email volume by 80 percent. Open rate climbed."), or an imperative ("Try this before your next send."). Each one immediately tells the reader's brain that the email has a point.
The throat-clear: the most common opening sin
"Hi everyone, hope you had a great week. Today I want to share something I've been thinking about lately." Twenty-six words. Zero information. Pure overhead.
The fix: cut the throat-clear entirely. Start with the first concrete sentence about your actual subject. Most newsletters improve dramatically with the simple deletion of their first paragraph. The salutation can move to a one-line PS at the bottom.
How to find your drop-off sentence
Every newsletter draft has one sentence in the first 100 words that the reader uses as the closing trigger. Finding it manually is hard - you wrote it, so you do not see the friction. Two techniques work:
- Read aloud. The sentence that makes you want to skim is the one that makes the reader want to close.
- Score every sentence mechanically. The hook tester ranks every sentence in the first 100 words by pull strength and surfaces the weakest one.
The repair pattern: cut the weak sentence entirely, or rewrite it so the verb does the work. Most often the right answer is to cut.
Patterns that consistently win
Across thousands of newsletters in the corpus, three opening patterns over-index for completion rate:
- The post-mortem: "Last week we did X. It failed. Here's why." Names the failure, promises the lesson.
- The contrarian claim: "Most advice on X is wrong. Here's what actually works." Sets up a payoff.
- The numbered trend: "Three things changed in our market this month." Reader knows exactly what they're getting.
Score your opening
The hook tester takes the first 100 words and returns a 0-100 score, the strongest sentence highlighted in green, and the drop-off risk highlighted in red. The live counter covers reading time and Flesch for the rest of the body.
Open the hook tester →Frequently asked questions
Why 100 words?
The empirical threshold above which engagement curves flatten. Below it, weak sentences cost a percentage of readers each.
What makes a strong opening?
Strong action verb, sentence-length variety, reader-centric framing, specificity, hook signal in sentence one.
Open with a story?
Yes if the payoff lands by sentence three. No if the story rambles past 50 words before paying off.
The worst opening?
The throat-clear: "Hi everyone, hope you had a great week..." Cut it entirely.
How do I find the drop-off sentence?
Read aloud or use the hook tester to score every sentence by pull strength.