Email Subject Line Grader
Score your subject line on 12 proven factors. Get instant feedback on length, power words, spam risk, personalization, and more. No signup. No cost.
0 characters
Your Score
Score Breakdown
Power Words Detected
Spam Triggers Detected
Improvement Suggestions
How the Subject Line Grader Works
Enter Your Subject Line
Type or paste your email subject line into the input field. The grader works with any length, but will tell you if yours needs adjusting.
Instant 12-Factor Analysis
Our algorithm scores your subject line across 12 weighted categories: length, power words, spam triggers, personalization, question format, numbers, urgency, caps ratio, emoji count, word count, action verbs, and mobile preview.
Actionable Recommendations
Get a detailed breakdown with specific suggestions for each category. See exactly which power words were detected, which spam triggers to avoid, and how to improve your score.
What the Grader Evaluates
Subject Line Grader FAQ
What makes a good email subject line?
A good email subject line is 28-50 characters long, includes one or two power words that trigger emotion or curiosity, avoids spam trigger phrases, and clearly communicates the value the reader will get by opening. Subject lines with numbers, questions, or personalization tokens also tend to perform well. Above all, the subject line should match the content inside the email.
How does the subject line grader score my subject line?
Our grader evaluates your subject line across 12 weighted categories: character length, word count, power word usage, spam trigger detection, personalization tokens, question format, numbers and statistics, urgency signals, capitalization ratio, emoji usage, action verb starts, and mobile preview friendliness. Each category contributes to a total score out of 100, and the tool provides specific tips for every area where you can improve.
What are email power words and why do they matter?
Power words are emotionally charged words that trigger a psychological response in readers. They fall into categories like urgency (e.g., "deadline," "final"), curiosity (e.g., "secret," "discover"), greed (e.g., "free," "bonus"), trust (e.g., "proven," "guaranteed"), and fear (e.g., "mistake," "warning"). Using one or two power words in your subject line can significantly boost open rates, but overusing them can feel manipulative or trigger spam filters.
Will using spam trigger words guarantee my email goes to spam?
No. Modern spam filters use hundreds of signals beyond just keywords, including sender reputation, authentication (SPF, DKIM, DMARC), engagement history, and sending patterns. However, spam trigger words do add negative weight to your overall spam score. A single "caution" level word in an otherwise well-authenticated email from a reputable sender is unlikely to cause problems. But stacking multiple critical-level trigger words absolutely increases your risk of landing in the spam folder.
How long should my email subject line be?
The ideal length is 28-50 characters. This range is long enough to communicate value but short enough to display fully on most devices. Mobile email clients typically show 30-40 characters, and desktop clients show 50-60. Subject lines over 70 characters get truncated nearly everywhere and tend to underperform. If you need more context, use preheader text (the preview text that appears after the subject line) to extend your message.