Email Subject Line Grader — Free 2026
Get an instant A-F grade on your email subject line. Know your predicted open rate before you hit send.
Aim for 30+ chars
A/B Variant Comparison (optional)
What We Analyze
Character Length
Optimal: 30–50 chars. Over 60 gets cut off on iPhone. Under 20 lacks context.
Spam Trigger Words
Words like "free," "act now," and "guaranteed" kill deliverability. We flag them all.
Power Words
Words like "you," "how," "new," and "proven" have statistically higher open rates.
Question Format
Subject lines posed as questions generate curiosity and consistently outperform statements.
Numbers & Specificity
"3 ways" beats "several ways." Numbers signal concreteness and credibility.
A/B Variants
Compare two or more subject lines side-by-side to find your best performer before sending.