Free tool
Email subject line tester
Check subject length and see approximate desktop and mobile inbox previews.
Free · No signup · Runs in your browser — nothing uploaded
An email subject line tester shows how long your subject is and how it may appear in a crowded inbox, including optional preheader text next to the sender name.
Enter your subject below for character counts, quick quality hints, and approximate desktop and mobile previews. Every email app truncates subjects differently — treat previews as guidelines.
Desktop
Your name
Your subject line
Mobile
Your name
Your subject line
Checks
- Chars 0 · Words 0 · Emoji 0
- CAPS 0%
- No promo hints (advisory)
FAQ
What is a good subject line length?
Many desktop clients show roughly 50–60 characters; mobile often shows fewer. Shorter, specific subjects usually outperform vague or all-caps lines.
What is preheader text?
Preheader is the gray snippet beside or below the subject in many inboxes. It often comes from the first text in your email body if you do not set it explicitly in your ESP.
Does this tool send my subject to Piisend?
No. Analysis runs entirely in your browser. Nothing is uploaded to Piisend servers.