Email Subject Line Preview and Length Checker
Shows how an email subject line will display and truncate across desktop Gmail, mobile Gmail, and Outlook, with a live character count.
How to Use This Tool
- 1 Enter your proposed email subject line.
- 2 Optionally type a preheader preview text snippet.
- 3 Input your brand or sender name to preview real inbox sender alignment.
- 4 Review side-by-side mockups showing truncation across Desktop Gmail, Mobile Gmail, and Outlook.
Navigating Inbox Truncation Points
Subject line length advice online is inconsistent mostly because different inboxes truncate at different points, and most advice does not specify which inbox it is talking about. Desktop Gmail generally shows more characters than mobile Gmail, and Outlook default preview pane behaves differently again.
A subject line that reads perfectly on desktop can get cut off mid word on a phone, which is where most email is actually opened first. The preheader (the short line of text that appears after the subject line in the inbox preview) gets ignored constantly, even though it is effectively free additional space to make the case for opening the email.
This tool renders the subject line and preheader against three common inbox layouts side by side, so the length problem is visible before the email goes out rather than after open rates come back lower than expected.