Email Subject Tester

Score your email subject lines against 8 key factors that drive open rates. Get instant feedback and specific recommendations to boost performance.

Enter Your Subject Line

0 charactersOptimal: 30-50 characters

What Makes a Great Subject Line?

✓ Do This

  • • Keep it 30-50 characters
  • • Use power words (free, exclusive, proven)
  • • Add personalization ({first_name})
  • • Include numbers for specificity
  • • Use 1 emoji strategically
  • • Create urgency (today only)

✗ Avoid This

  • • ALL CAPS words
  • • Spam triggers (FREE!!!, Act Now)
  • • Excessive punctuation (!!!???)
  • • Multiple emojis (🎉🎊🎁💰)
  • • Misleading promises
  • • Being too vague or generic

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Frequently Asked Questions

The optimal length is 30-50 characters or 6-10 words. This ensures full visibility on most devices. Mobile shows ~35 characters, desktop Gmail ~60 characters. According to Campaign Monitor's research, subject lines under 50 characters have higher open rates.

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