Free tool

Email Subject Line Generator

Describe your email and who it's for. You get ten subject lines, each with why it works and when to use it.

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Short answer

Email Subject Line Generator: what it does

A good subject line promises something specific the reader already wants, or names a problem they're feeling right now. It doesn't trick people into opening — it makes the contents obvious enough that the right people open.

Last updated 3 August 2026

Worked example

Here's one we ran earlier.

A £29/month booking app for independent UK hair salons, emailing owners about a no-show policy template

The no-show policy salons actually use
Highest open
Leads with the thing the reader wants, not the sender. Works because it sounds like the content, not a promotion.
How much did no-shows cost you last month?
Pain-led
Asks a question the reader already has an answer to. Best for a list that has felt the pain recently.
Template: deposit wording that doesn't sound rude
Utility-led
Specific and useful. The word 'template' signals low effort, and the body should deliver exactly that.

How it works

Three steps, no account.

Step 1

Say what the email is actually about

The subject line is a promise. If the body doesn't keep it, you get opens but lose trust. Trust is worth more than one open.

Step 2

Pick one person to write for

A subject line that works for everyone works for no one. Write it for the one segment who will find it most relevant, even if everyone else ignores it.

Step 3

Test the first three against each other

Don't run ten subject lines at once. Pick the three that feel most different, send them to small slices of your list, and send the winner to the rest.

Questions

Common questions.

How long should a subject line be?

Under 50 characters so it doesn't get cut off on mobile. That usually means six to eight words. If you can't fit the promise in that space, the email is probably trying to do too much.

Should I use emojis in subject lines?

Only if they match your brand and the email's tone. They can lift opens in casual markets and hurt them in professional ones. Test one against a plain version rather than guessing.

Do personalisation tokens like first name still work?

Less than they used to. Most inboxes are full of first-name subject lines. Personalisation that works now references behaviour, like a feature they used or a report they downloaded.

What's a good open rate?

20–25% for a warm list, 15–20% for a colder one. If you're below 15%, the problem is usually the list quality or the sender reputation, not the subject line.