Newsletter Preheader Previewer
Enter newsletter sender, subject, and preview text to compare simple narrow, standard, and wide inbox summaries before sending.
A QUICK WALKTHROUGH
How to use this tool
- Enter the sender name, subject, and preheader text.
- Review the summaries at three representative text widths.
- Use the character counts as guidance and check the final message in your chosen email clients.
Character counts are guidance
Counts use JavaScript UTF-16 code units and include spaces and punctuation. Inbox summaries may wrap, truncate, reorder, or hide fields according to the client and device.
Approximation only
This tool makes no network request and does not reproduce any named email client. Font metrics, device width, localization, notification settings, and client-specific rules can change the visible result.
GOOD TO KNOW
Common questions
Does this match my email client exactly?
No. It is a local text approximation across three representative widths, not an exact client screenshot or rendering guarantee.
What is counted?
Each field shows its JavaScript UTF-16 character count, including spaces and punctuation.
Are my newsletter details uploaded?
No. The preview runs in this browser and makes no network request.