Free AI copywriting tool · no sign-up
Free AI Email Subject Line Generator
Describe your email and get 10 high-converting subject lines designed to boost open rates — most kept short enough to display in full on mobile.
What gets an email opened
Subject lines live or die on the first ~40 characters shown on mobile. The best ones spark curiosity or promise a clear benefit, feel personal, and avoid spam-trigger words. Numbers, questions, and a touch of urgency reliably lift open rates.
Subject line best practices
- Keep it under ~50 characters so it shows in full on phones.
- Lead with the benefit or the curiosity gap.
- Avoid ALL CAPS and spammy words ("free!!!", "act now").
- Match the subject to the content — never bait-and-switch.
Frequently asked questions
How long should an email subject line be?
Aim for under about 50 characters so it displays fully on mobile, where most emails are opened.
How do I increase open rates?
Lead with a clear benefit or curiosity, personalise where you can, keep it short, and avoid spam-trigger words. Test two subject lines against each other.
Is it free?
Yes — free, no sign-up, fair hourly limit.