Subject Line Tester
Analyze and improve your email subject lines for better open rates
Why Your Subject Line Matters
The email subject line is the first thing recipients see and it significantly influences whether your email gets opened or ignored. A well-crafted subject line can dramatically increase your open rates, while a poor one can send your email straight to the trash folder – or worse, the spam folder.
How This Tool Helps
Our subject line tester analyzes your subject line for key factors that affect open rates and deliverability, including length, spam trigger words, formatting issues, and overall engagement potential. The tool provides actionable feedback to help you optimize your subject lines for better results.
Test Your Subject Line
Subject Line Best Practices
What Makes a Great Subject Line?
- Concise: 4-9 words (30-50 characters) typically perform best
- Clear: Communicate a single, clear message
- Specific: Avoid vague or generic statements
- Personalized: Include recipient's name or relevant details when possible
- Curious: Create curiosity without being misleading
- Urgent: Create a sense of timeliness when appropriate
Subject Lines to Avoid
- ALL CAPS or excessive punctuation (e.g., "FREE OFFER!!!")
- Misleading subject lines that don't match email content
- Generic subject lines like "Newsletter" or "Monthly Update"
- Spam trigger words like "free," "guarantee," "no cost," etc.
- Symbol overuse like "$$$" or "★★★"
Subject Line Formulas That Work
- How-to: "How to [achieve desired outcome] in [timeframe]"
- Question: Ask a relevant question that resonates with the recipient
- List: "5 Ways to [solve a problem]"
- Announcement: "Introducing: [new product/feature]"
- Urgency: "Last day to [take advantage of offer]"
- Curiosity gap: "The unexpected reason [common problem occurs]"
A/B Testing
The most reliable way to improve subject lines is to test different versions with your actual audience. When A/B testing subject lines:
- Test only one variable at a time (length, tone, personalization, etc.)
- Use a statistically significant sample size
- Track both open rates and click-through rates
- Apply insights from winning subject lines to future campaigns
Need More Help?
Crafting the perfect subject line is just one part of email marketing success:
- Check for spam trigger words with our Spam Word Analyzer
- Preview how your emails will appear with our Inbox Preview Simulator
- Create a free Buffsend account for more email marketing tools and support
