AI Email Subject Line Generator
Generate email subject lines tuned to your tone, industry, and campaign — with character counts, spam-word checks, and saved subject lines for the keepers.
Your subject lines appear here
Each one comes tagged with its angle, a character count, and a spam-word check. Star the keepers to save them below.
Generating subject lines...
Subject lines ·
Over 41 characters may truncate on mobile. Test your top 2–3 against each other.
Saved subject lines
Save subject lines you like and they'll collect here — saved in this browser and ready to share with a restorable link.
· · chars ·
Nice saved list. Want to know which one actually wins?
Metorik Engage sends your emails to the right customers and tracks opens, clicks, and revenue per campaign — so your best subject line is a fact, not a guess.
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Use toolWriting subject lines is the worst part of sending email
You've built the campaign, picked the products, written the email — and now you're staring at an empty subject field, because the one line that decides whether anyone reads the rest is somehow your job too.
That's the whole reason this tool exists. Give it your topic, pick a tone, and it'll hand you ten options — each tagged with the angle it's playing (urgency, curiosity, benefit, a question) so you're choosing between genuinely different ideas, not ten versions of the same one. Save the keepers and they'll wait in your saved subject lines for next time.
How long should a subject line be?
Under about 41 characters if you want the whole thing to show on a phone, which is where most of your opens happen. Longer isn't wrong — just put the meaning up front and let desktop readers enjoy the rest. The character count next to each line goes amber when you're past the mobile cutoff, so you'll know before your subscribers do.
And write your preview text as the second half of the thought, not an afterthought. The subject earns the glance; the preview closes the open.
A word on spam triggers
Filters don't ban words, they keep score — and "FREE!!!", "act now", "winner", and "100% guaranteed" all add points. One mild trigger from a sender with a good reputation is fine. A pile of them isn't. We flag the common ones with a ⚠ so it's a choice, not an accident. Usually there's a calmer phrasing that works just as well: "on us" instead of "FREE", "ends Sunday" instead of "ACT NOW".
Don't pick a winner — test one
Everyone's sure they can spot the best subject line, and everyone's wrong about half the time. Take your top two or three (different angles, not different commas), split part of your list between them, send the winner to the rest. And judge on what happens after the open — a clickbait line can win the open rate and lose the sale.
That last part is where this tool taps out and your email platform takes over. If you're on WooCommerce or Shopify, Metorik Engage tracks opens, clicks, and revenue per campaign, so "which subject line works" becomes a number, not a feeling.
AI Email Subject Line Generator FAQs
Can't find what you're looking for below? Read our Help Docs
Is it free?
Yes — no signup, no email gate. The lines are yours, and your saved subject lines live in your browser with a shareable restore link.
Do emojis help open rates?
Sometimes. They stand out in a crowded inbox, and they suit some brands much better than others. The emoji setting makes it easy to generate with and without and test the difference.
Does first-name personalization actually work?
Modestly, and only when the rest of the line is relevant too. A name stapled to a generic line reads like a mail merge. Personalizing what you send beats personalizing the greeting.
How do I know which line performs best for my store?
Send your top picks to slices of your list and compare clicks and revenue, not just opens. Metorik Engage does that tracking automatically for WooCommerce and Shopify stores.
Still have questions?
Can't find the answer you're looking for? Chat to our friendly team.