Free tool by Crom Salvatera
Hook And Subject Line Analyser
Write openers people stop for, open, and act on.
This subject line analyser scores LinkedIn hooks, email subject lines, and Meta ad primary text live for emotional pull, channel fit, hook strength, and clarity. Then fix your copy in seconds with ranked suggestions and proven formulas.
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Quick answer
What Is A Subject Line Analyser?
A subject line analyser is a tool that scores the opening words of your copy for how likely they are to earn attention. This one checks LinkedIn hooks, email subject lines, and Meta ad primary text for emotional pull, fit within each channel’s cut-off, hook strength, and clarity, then ranks the fixes. Use it before you post, send, or launch.
If you searched for a subject line analyzer with the US spelling, or an email subject line tester, you are in the right place. The Crom Salvatera Hook and Subject Line Analyser runs on the same engine as my Headline Analyser, then adds the rules each channel plays by. Pick a channel, paste your copy, and in a few seconds you get a score out of 100, your top three fixes, a live preview, and scored rewrites.
30% of your score
Emotion
EMV words plus the human needs, wants, and emotive triggers your opening reaches. Scored on the words people see first.
25% of your score
Channel Fit
Length against each channel’s cut-off, preview text, spam-style punctuation, fake replies, and ad policy risks.
25% of your score
Hook Pull
A number, a question, a direct “you”, real tension, and a specific detail. Penalties for throat-clearing and clickbait.
20% of your score
Clarity
Vague words, jargon, passive voice, and shouting capitals in your opening line. Easy to read at a glance wins.
Why one tool for three channels
Three Channels, Three Different Jobs
A LinkedIn hook, an email subject line, and a Meta ad all do the same thing: they win the first second of attention. Each platform cuts your words off at a different point and plays by different rules, so a subject line analyser that only counts characters misses most of what matters.
1 line
LinkedIn Hook
LinkedIn shows only the opening of a post before “see more”. The hook line has one job: earn the tap. The analyser scores your first line and previews it at phone and desktop width.
2 lines
Email Subject Line
The subject and the preview text work as a pair in most inboxes. Gmail asks bulk senders to avoid deceptive subject lines, so fake “RE:” tricks lose points here.
50-150
Meta Primary Text
Meta’s ads guide suggests 50 to 150 characters of primary text for Facebook Feed image ads. This subject line analyser checks length and flags copy that could break Meta’s personal attributes rule.
The science inside the score
Built On The Human Influence Layers I Teach
Every opener is checked against my framework for why people buy: 8 natural human needs, 9 learned human wants, and 7 emotive triggers. I built it over 22+ years and 500+ ad accounts, and my Rule of 1-2-3 shows how to stack them so a single line pulls on several levels at once. The subject line analyser tells you how many layers your words reach. Which ones, and how to combine them, is what I teach.
8
Natural Human Needs
The deep, instinctive drives that make people stop scrolling. Touch one and you earn a second look.
9
Learned Human Wants
The desires culture teaches us. Some of the most commercially powerful forces in a feed or an inbox.
7
Emotive Triggers
The emotional levers that turn a glance into a tap, an open, or a click. Stack them with needs and wants.
Hooks, answered
What Makes A Good LinkedIn Hook?
A good LinkedIn hook is one short first line that makes a specific promise, names a problem, or creates tension the reader wants resolved. It sits on its own line, keeps hashtags and links for later, and skips throat-clearing such as “I’m excited to share”. In my experience, the best hook lines run under about 70 characters, so they land before anything else on the screen.
Across 22+ years in marketing and 500+ ad accounts I have managed and optimised, the openers that win share the same shape: a real stake, a concrete detail, and a promise the rest of the post keeps. The subject line analyser rewards all three and shows a phone and desktop preview, so you can see where “see more” is likely to fall.
What Is A Good Email Subject Line Length?
Aim for about 50 characters or fewer and 9 words or fewer, with the most important words first. Many email apps cut long subject lines off, especially on phones, so a short subject paired with useful preview text usually does more work than one long line.
This subject line analyser checks length, word count, spam-style punctuation, emoji overload, and fake reply or forward prefixes. It also checks whether your preview text adds something new or simply repeats the subject. Add your preview text in the field that appears when you choose Email Subject Line.
How Long Should Meta Ad Primary Text Be?
Meta’s ads guide recommends 50 to 150 characters of primary text for Facebook Feed image ads. Longer copy can still work for some offers, but only the opening shows before “See more”, so the hook and the offer belong in the first sentence.
Meta’s Advertising Standards also say ads must not assert or imply personal attributes, such as a person’s health, financial status, age, or religion. Openers like “Struggling with debt?” can get an ad rejected, so the subject line analyser flags them and suggests leading with what the product does.
Use it like a pro
How To Write A Better Hook In 5 Steps
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Pick The Channel First
A LinkedIn hook, a subject line, and ad text get cut off at different points. Write to the space you actually get.
-
Lead With The Stake
Open with the result, the problem, or the surprise. Save the greeting and the backstory for later.
-
Add One Specific Detail
A number, a timeframe, a place, or the audience makes the promise believable in one glance.
-
Keep It Honest And Policy-Safe
No fake “RE:”, no curiosity bait, and no claims about the reader’s health, money, or identity in ads.
-
Score, Compare, And Pick A Winner
Paste three to five options into the Compare tab, then test the top two with real readers.
What Is An Example Of A Strong Hook?
A strong email subject line example is “3 email mistakes quietly costing you sales”, which scores 83 out of 100 in this subject line analyser without preview text. It opens with a number, names a cost the reader wants to avoid, and stays short. “Monthly Newsletter: October Edition” scores 45, because it gives the reader no reason to open. “RE: Your account” scores 30, because a fake reply prefix costs trust.
The same pattern holds on LinkedIn and Meta. Type any of these into the tool above to see exactly where the points come from.
| Opener | Channel | Score |
|---|---|---|
| 3 email mistakes quietly costing you sales | Email Subject Line | 83 |
| Your 5-minute SEO checklist for November | Email Subject Line | 76 |
| Monthly Newsletter: October Edition | Email Subject Line | 45 |
| RE: Your account | Email Subject Line | 30 |
| Stop wasting money on ads that do not work. | LinkedIn Hook | 77 |
| I’m excited to share some news with my network today! | LinkedIn Hook | 57 |
| Stop guessing which ads work. Get a clear 90-day plan for your Meta ads, built around your margins. Book a call. | Meta Primary Text | 69 |
| Struggling with debt? Our advisers can help you get back on track today. | Meta Primary Text | 41 |
| Shop now!!! HUGE sale on EVERYTHING!!! | Meta Primary Text | 49 |
Who it is for
Who Is This Subject Line Analyser For?
Founders On LinkedIn
Test the first line of every post before it goes out, and stop burying the point under a greeting.
Email Marketers
Check subject lines and preview text as a pair, and catch spam-style habits before they reach the inbox.
Meta Advertisers
Keep primary text in Meta’s suggested range and catch personal attribute wording before an ad gets rejected.
Not For Predicting Results
No tool can see LinkedIn’s, Gmail’s, or Meta’s data. Treat the score as a sharp second opinion, then test.
Go further
Want To Write Hooks Like This Without A Tool?
My copywriting course teaches the full method behind the score: how to stack needs, wants, and emotive triggers on purpose, and how to write openers that earn the next line on every channel.
FAQ
Frequently Asked Questions About Subject Line Analysers
Is A Subject Line Analyser Accurate?
A subject line analyser accurately measures what it checks, such as length, emotional words, and spam-style habits. It cannot predict open rates, reach, or clicks, because no tool has access to Gmail’s, LinkedIn’s, or Meta’s data. Use it to compare options, then test with real readers.
Does Starting A Subject Line With RE: Work?
It is a trick, and tricks cost trust. Gmail’s bulk email guidance asks senders to avoid deceptive subject lines, so this analyser treats a fake “RE:” or “FW:” on a first email as a trust risk.
Should I Use Emojis In Subject Lines And Hooks?
In my experience, one emoji can help a line stand out, and more than one tends to read as noise. This subject line analyser allows one and flags more. Test a version with and without, because results vary by audience.
Why Would Meta Reject My Ad Text?
A common reason is wording that asserts or implies a personal attribute, such as “Are you in debt?” or “Depression getting you down?”. Meta’s Advertising Standards do not allow it. Talk about what your product does, and the subject line analyser will stop flagging it.
How Is This Different From The Headline Analyser?
Both use the same engine for emotion and clarity. The Headline Analyser is built for titles that rank in Google and AI answers. This tool is built for the opening words of posts, emails, and ads, with each channel’s cut-offs and rules.
Is My Copy Stored Anywhere?
No. The subject line analyser runs entirely in your browser. Nothing you type is sent to a server or saved, so you can test unpublished campaigns safely.
What to do next
Turn Better Hooks Into More Leads
A strong opener names a real stake, fits the space the channel gives it, makes a specific promise, and keeps it honestly. Run every hook, subject line, and ad through this subject line analyser and compare at least three options before you publish.
Want a content and social strategy that turns better hooks into more enquiries? Read how I approach copywriting and the principles of consumer psychology, then talk to me.
About Crom Salvatera
Crom Salvatera is a Sydney-based AI marketing consultant and Head of SEO, AEO and GEO with 22+ years in marketing and 14 in high-level digital. He has managed and optimised 500+ ad accounts, has helped generate $650M+ in revenue for employers and clients, and created the TLC Method (Tech, Links, Content). His brand experience includes LEGO, Hasbro, JB Hi-Fi, and Crimson Education. Connect with him on LinkedIn.
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