Free AI tool
AI email subject line generator
Describe your email, pick a tone and get 10 original subject lines you can use right away. Powered by AI, free and unlimited.
Your subject lines
Generated by AI. Review each subject line before you send, and adapt it to your audience.
Want a second opinion? Score any of these with our free subject line tester.
The subject line decides whether your email gets opened or ignored. This free AI email subject line generator turns a one-sentence description of your message into 10 ready-to-use ideas that stay within the 30 to 50 character sweet spot, avoid spam trigger words and cover different angles: benefit, curiosity, urgency and plain clarity. Write in any language and the generator answers in the same one, which makes it just as useful for international campaigns as for your next internal update.
How to use the AI subject line generator
- 1
Describe what your email is about in one or two sentences. The more specific you are, the sharper the suggestions.
- 2
Pick the tone that matches your audience: professional for B2B outreach, playful for a community newsletter, urgent for a deadline.
- 3
Click "Generate subject lines" and wait a few seconds while the AI writes 10 options.
- 4
Copy the line you like best with its Copy button, or copy the whole list to compare them in your draft.
- 5
Test your favorite in our subject line tester, then paste it into your campaign and send.
Frequently asked questions
Is this AI subject line generator really free?
Yes. There is no signup, no credit card and no daily paywall. We built it as a free companion to Mail Merge for Gmail, our tool for sending personalized campaigns from Google Sheets.
How long should an email subject line be?
Aim for 30 to 50 characters. Most mobile inboxes truncate somewhere in that range, so shorter lines survive intact. The generator targets that window by default and puts the most important words first.
Will these subject lines trigger spam filters?
The generator is instructed to avoid the classic spam patterns: ALL CAPS, stacked exclamation marks and trigger phrases like "act now" or "100% free". Deliverability still depends on your sender reputation and list quality, so pair a clean subject line with a warmed-up domain and a permission-based list.
Can I generate subject lines in languages other than English?
Yes. Describe your email in any language and the AI replies in that language. This works well for localized campaigns where a literal translation of an English subject line would sound unnatural.
How do I know which of the 10 subject lines will perform best?
Run an A/B test if your volume allows it: send two variants to a small slice of your list and roll out the winner. For a quick sanity check before sending, paste candidates into our free email subject line tester, which scores length, clarity and spam risk.
Can I personalize these subject lines for each recipient?
Yes, and it usually lifts open rates. Add a merge tag like {{firstName}} or the recipient's company to the line. Mail Merge for Gmail fills those tags automatically from your Google Sheet when the campaign goes out.
Great subject lines deserve great campaigns
Send personalized email campaigns from Google Sheets with Mail Merge for Gmail: merge tags, tracking, scheduling and follow-ups.