โœ‰๏ธ Email Tool

Email Subject Line
Checker

Check your subject line and preview text against real inbox display limits, with a live preview. Free, instant, no signup.

โœ‰๏ธ Email Subject Line & Preheader

Target 30-50 characters. iPhone shows ~40, Gmail app ~37, desktop ~60-70.

Target 40-90 characters โ€” this is your second headline.

Inbox Preview
Your subject line
Your preview text will appear here, next to the subject line

๐Ÿ“ Character Limits Reference

FieldLimitNotes
Subject line (recommended)30โ€“50Optimal balance of clarity and mobile visibility
iPhone Mail (portrait)~35โ€“40 visibleShortest common display
Gmail app (Android)~37 visible
Gmail desktop~60โ€“70 visible
Outlook desktop~60 visible
Preview text / preheader40โ€“90Second headline shown after subject
Cold outreach subject2-4 wordsBelkins data: shortest subject lines had the highest open rate
B2B newsletter subject6-10 wordsLonger lines drove more clicks in B2B specifically

Was this tool helpful?

Also check your copy for:

๐Ÿ” Meta Description Checker ๐Ÿ“ Word Counter ๐ŸŽฏ Google Ads Counter ๐Ÿ’ผ LinkedIn Counter
Related Guides

Write better copy within the limits.

Guide

Email Subject Line Length 2026: The Complete Data-Backed Guide

30-50 characters is the sweet spot โ€” here's the research and device-by-device breakdown.

๐Ÿ“– 7 min read Preheader

Email Preview Text (Preheader): The Underused Second Headline

Most marketers leave it blank. Here's how to use the 40-90 character preview text field.

๐Ÿ“– 5 min read Outreach

Cold Email Subject Lines: What 5.5 Million Emails Reveal About Length

Shorter wins for cold outreach โ€” the data on 2-4 word subject lines.

๐Ÿ“– 6 min read

Frequently Asked Questions

Common questions about character limits and how the tool works.

The reliable target is 30-50 characters (roughly 7-9 words). This is descriptive enough for clarity while staying visible on mobile devices, which show fewer characters than desktop clients.
An iPhone in portrait mode typically shows only 35 to 40 characters of a subject line, compared to around 60 characters on a desktop Gmail client. Front-load your most important words.
Preview text is the snippet that appears after the subject line in most inboxes. Setting deliberate preview text of 40 to 90 characters gives you a second line of subject copy, effectively doubling the information communicated before the open.
It depends on the email type. Cold outreach performs best with very short (2-4 word) subject lines. B2B newsletters and educational content often perform better with longer, 6-10 word subject lines that provide more context.
Yes, completely free with no signup. It checks your subject line against the 30-50 character target and shows a live inbox preview alongside your preheader text.