All tools free. No signup. No limits. Ever.

Email Subject Line Tester

Score your email subject lines for effectiveness. Check for spam triggers, analyze length, and get actionable improvement tips.

Free Tool

Enter a subject line above to analyze...

/ 100
Enter subject line
0
Characters
0
Words

Why email subject lines matter

Your subject line is the first impression your email makes. It determines whether someone opens it or sends it to trash. Studies show that 47% of email opens are based on subject line alone. A compelling subject line can increase your open rate by 50% or more. Testing and optimizing subject lines is one of the highest-ROI activities in email marketing.

What makes a great subject line

Great subject lines are specific, create curiosity or urgency, and deliver on their promise. Use personalization when possible. Include numbers (they increase click-through rates). Keep it concise — most email clients show only 35-50 characters on mobile. Test different subject lines to see what resonates with your audience. Avoid spam trigger words and excessive punctuation.