Free AI Email Subject Line Generator
Paste your email or describe what it's about. Get 5 high-open-rate subject lines in seconds — tailored for sales, cold email, newsletters, or any use case. No signup required.
Generators for every use case
Need subject lines for a specific type of email? Use a dedicated generator below.
50+ proven email subject line examples
A swipe file of high-performing subject lines, organized by use case. Copy, adapt, or paste them into the generator above and ask for variations.
Sales follow-up
- Quick question about {{company}}
- Worth 15 minutes next week?
- Did this get buried?
- {{firstName}}, one more thought on [topic]
- Re: our conversation about [topic]
Cold outreach
- {{firstName}}, noticed something about {{company}}
- How {{competitor}} handled [problem]
- 3 ideas for {{company}}
- Saw your post on [topic] — small thought
- Question about your [specific workflow]
Newsletter
- What changed this week
- The one thing we learned about [topic]
- 5 links worth your time
- Our take on [recent event]
- Why we're betting on [trend]
Product update
- New: [feature] is live
- You asked, we shipped
- Small update, big difference
- [Feature]: now 3x faster
- What we shipped this month
Meeting request
- 15 min this week?
- Finding time for [topic]
- Quick sync re: [project]
- Does Thursday at 2pm work?
- Open to a short call?
Thank you / appreciation
- Thank you for [specific thing]
- That really helped — here's why
- Appreciated our conversation
- Grateful for the intro
- One more thank you
Apology / issue
- An update on your [issue]
- Following up on [incident]
- Here's what happened and next steps
- Quick update re: [problem]
- We made a mistake — here's the fix
Event / webinar invite
- [Date] — you're invited
- Join us: [topic] with [speaker]
- Quick heads up about [event]
- Last chance: [event name]
- Save your seat for [event]
Re-engagement
- Still interested in [topic]?
- Should we stay in touch?
- It's been a minute — here's what's new
- One last check-in
- Haven't heard from you — all good?
Transactional / confirmation
- Your [item] is confirmed
- Receipt for your [order]
- Welcome to [product]
- Action needed: verify your email
- Your [report] is ready
How to write email subject lines that get opened
1. Keep it under 60 characters
Mobile clients truncate subject lines past ~40 characters, and desktop clients often cut off at 60. The first 30 characters do the heaviest lifting. Front-load the value.
2. Be specific, not clever
"Quick question about your hiring process" beats "Got a sec?" every time. Specificity signals you're a real person with a real reason to email.
3. Personalize when it's honest
Using the recipient's first name or company increases opens by ~22% (Campaign Monitor, 2024). Personalization tokens that clearly look automated hurt more than they help. "Sarah, noticed your launch" works. "Hey [FNAME]!!! works for YOU" does not.
4. Avoid spam triggers
Skip ALL CAPS, excessive punctuation, and spammy phrases: "FREE," "URGENT," "ACT NOW," "GUARANTEED," "LIMITED TIME," "WINNER." Modern spam filters flag these instantly. Emojis are OK in moderation but avoid them in B2B.
5. Match the subject to the email body
Misleading subject lines tank trust and trigger spam complaints, especially at scale. Your subject line is a promise — the body has to deliver on it.
6. A/B test the top two
If you're sending at volume (newsletters, campaigns), generate 5 options with the AI, shortlist your top 2, and split-test. Most email platforms (Mailchimp, Beehiiv, ConvertKit) have built-in A/B testing.
Need more than a free tool?
Like this subject line generator? The Aeralis Gmail add-on does this and more, right inside your inbox.
Free tier includes 15 emails/month. No credit card required.
Frequently Asked Questions
Common questions about our subject line generator
How many subject lines do I get per generation?
Each generation gives you 5 distinct subject line options, each with a different angle (curiosity-led, benefit-led, direct, personal, and short-form). Pick whichever fits your email best.
What is the ideal length for an email subject line?
Aim for 6–10 words or 40–60 characters. Subject lines longer than 60 characters get truncated on mobile, and very short ones (under 20 characters) can look vague. Data from Mailchimp and HubSpot shows 41–50 characters is the sweet spot.
What makes a good email subject line in 2026?
Good subject lines are specific, clear about the value, and avoid spam triggers. Personalization (first name or company name) lifts opens by 22% on average. Curiosity works, but vague "clickbait" subjects kill trust. Skip ALL CAPS, exclamation marks, and words like "FREE," "URGENT," "ACT NOW."
Can I use this for cold email subject lines?
Yes. This tool works for cold outreach, sales follow-ups, and prospecting emails. For best results, paste the full body of your cold email — the AI uses that context to write subject lines that match the email content, which is critical for avoiding spam filters.
Can I use this for newsletter or marketing subject lines?
Yes. It works for newsletters, promotional emails, product updates, and transactional emails. Provide a short description of your newsletter content and the AI returns 5 subject line variations optimized for open rates.
What subject line words cause emails to land in spam?
Common spam triggers include: "FREE," "ACT NOW," "CLICK HERE," "GUARANTEED," "LIMITED TIME," "WINNER," "URGENT," and multiple exclamation marks. ALL CAPS subject lines and excessive emojis also trigger spam filters. Our AI avoids these automatically.
Is this subject line generator really free?
Yes! You can generate up to 10 sets of subject lines per hour completely free. No signup, no credit card, no email required. For unlimited generation inside Gmail, check out the Aeralis Gmail add-on.
How accurate is the AI-generated output?
The AI is powered by Google Gemini 3 and produces strong first drafts based on thousands of high-performing subject lines. We still recommend A/B testing 2–3 variants before a large send.
What makes this different from HubSpot or CoSchedule subject line tools?
Most subject line tools are template generators — you pick from pre-written patterns. This uses generative AI to write subject lines tailored to your actual email content. It reads what you paste and adapts. The Aeralis Gmail add-on goes further by learning your personal writing style from forwarded sent emails.
Want more email writing help? Read 5 Tips for Better Emails or try the Free AI Email Writer.
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