AI Email Subject Line Generator
Generate 10 subject lines engineered for high open rates — free, no sign-up required.
How it works
Describe your email
Enter the email topic, audience, and desired tone. The more specific you are, the better the subject lines.
AI generates 10 subject lines
The AI applies 15 proven psychological formulas — curiosity gap, urgency, social proof, personalization, and more.
Pick, test, and send
Copy your favourite line directly. For best results, A/B test 2 variations in your email platform.
15 subject line formulas that lift open rates
The average office worker gets 121 emails per day. Your subject line has 0.3 seconds to stand out. These 7 formulas account for the highest-performing subject lines across industries.
Curiosity gap
“I almost didn't send this email...”
Personalization
“Your Q3 marketing strategy (honest review)”
Numbers & specificity
“17 subject lines with 40%+ open rates (swipe file)”
Pattern interrupt
“RE: quick question”
Direct benefit
“Cut your churn rate by 23% — here's how”
Urgency + scarcity
“Closes tonight: founding member pricing”
Question
“Are you making this email mistake?”
Who uses an AI email subject line generator?
Email marketers
Generate and A/B test subject lines for newsletters, product announcements, and promotional campaigns.
Cold email outreach
Stand out in crowded inboxes with subject lines personalised to ICP pain points and job titles.
E-commerce brands
Write urgency-driven subject lines for flash sales, cart abandonment, and post-purchase sequences.
SaaS onboarding
Keep trial users engaged with benefit-led subject lines that guide them to activation events.
Newsletter creators
Publish a 40%+ open-rate newsletter consistently by testing different subject line formulas each week.
Agencies & freelancers
Scale client email results without writing every subject line from scratch. Generate, tweak, deliver.
Frequently asked questions
How long should an email subject line be?
40–60 characters for most email clients. Mobile cuts off after ~40 characters, desktop after ~60. Our generator shows you the character count so you can keep it in range.
Does the subject line affect deliverability?
Yes. Spam-trigger words (FREE!!!, CLICK NOW, ACT IMMEDIATELY) can route emails to the spam folder. Our AI avoids these patterns by default.
Should I use emojis in subject lines?
It depends on your audience. B2C and e-commerce lists often benefit from a single relevant emoji (+3-5% open rate on average). For B2B and executive audiences, plain text typically outperforms.
How many subject lines should I A/B test?
Test 2 variations per send. Any more splits your audience too thinly for statistically significant results. Pick the winner after 4 hours and send to the remainder.
Can I generate subject lines in other languages?
Yes — sign up for a free SwiftCopy account and set the output language to Spanish, French, German, Turkish, or 22 other languages.
What's included with a free SwiftCopy account?
3 AI generations per day across all 27 templates — including email subject lines, ad copy, social posts, hooks, and more.
Need more than 3 free uses per day?
Create a free account and get 3 AI generations daily across all 27 copy templates.
Start free — no credit card →