Email Subject Tester

Email subject lines determine whether your message gets opened or ignored. Studies show that 47% of recipients decide to open an email based solely on the subject line. The ideal length is 6-10 words or 40-60 characters — long enough to be descriptive, short enough to display fully on mobile.

Effective subject lines create curiosity or urgency without being clickbait. Personalization (using the recipient's name or company) increases open rates by 20-26%. Numbers and specifics outperform vague promises — "5 tips to reduce churn by 30%" beats "Tips to improve your business."

Avoid common spam triggers: ALL CAPS, excessive punctuation (!!!), and words like "free," "guarantee," or "act now." Emojis can help in B2C but hurt in B2B. A/B testing is the gold standard — but this tool gives you instant feedback on length, readability, and common pitfalls before you send.