Email subject and preheader preview
Preview supplied newsletter subject and preheader combinations.
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Your results
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How it works
Compare a From name, subject and preview text under a selected editorial character budget. Preview text provides a short glimpse of the message beside its subject. Lead with useful details and let the preheader support the subject. The tool counts Unicode grapheme clusters separately from code points so an accented letter or combined emoji is not automatically treated as several visible characters. Mailchimp reference: https://mailchimp.com/help/about-preview-text/.
A few things to know
This is a plain-text approximation, not an email-client screenshot or HTML preview. Actual visibility depends on font widths, inbox layout, viewport, sender display, client settings and how the email body implements preview text. Sender, subject and preheader budgets are independent here; some clients share horizontal space. Merge tags are not expanded, HTML is not interpreted, and no email is sent. The tool does not score spam risk, predict open rates or verify deliverability. Test the finished email in your audience’s actual clients before sending.
When to use this tool
An email’s subject, sender name and preview text work together before someone opens it. This text preview helps you see whether the useful details appear early within a chosen character budget. It counts visible character clusters where browser support allows and flags empty fields, repetition and overflow. The mobile and desktop presets are editorial approximations, not measurements of a specific inbox. Use them to refine a draft, then test the finished email in real clients.
- Check whether an offer or deadline appears before likely truncation.
- Write a preheader that adds context rather than repeating the subject.
- Review emoji and accented text without relying solely on raw code-point counts.
How to use email subject and preheader preview
Enter the three inbox text fields
Supply a recognizable From name, a subject and preheader. This tool treats them as literal text. Merge tags are not expanded, and HTML does not become a rendered email.
Choose an illustrative budget
Select mobile or desktop. Optional whole-number overrides from 1–500 can replace the independent sender, subject and preheader budgets. Leave overrides blank to use the preset values.
Review emphasis and repetition
Read the approximate visible text, hidden-character counts and review notes. Move essential information earlier where useful. Then test your actual email implementation and personalization in the clients your audience uses.
Review a mobile newsletter draft
Inputs
Use From name Small Hours, subject Your next great idea starts small ✨ and preheader Try three practical tools for a more profitable week. Select mobile without overrides.
Result
The subject contains 35 characters and fits its 35-character budget. The preheader contains 53 and exceeds its 50-character budget by three. The approximate preview truncates after profitable we and adds an ellipsis.
What it means
The essential practical-tools message remains early, while the ending may be shortened under this editorial budget. The result does not establish exactly what Gmail or Outlook will display.
Common mistakes to avoid
Putting all the value at the end
If an important offer, time or action appears only after the preview budget, some readers may never see it. Reorder the message rather than merely shortening punctuation.
Repeating the subject in the preheader
The preview field is a chance to add a useful detail. Repeating the subject spends that space without providing another reason to understand or open the message.
Treating characters as pixels
Letters have different widths and inbox layouts differ. Independent character budgets are useful editing constraints, but they cannot reproduce a client screenshot.
Frequently asked questions
Definitions, edge cases, and practical next steps for this tool. Search all tool FAQs ↗
What is preheader or preview text?
It is the short message excerpt shown near a subject in some inbox layouts. It can add context to the subject, such as an offer detail or next action. This tool reviews the text you intend to use; your email builder must implement it correctly.
Are the presets actual Gmail or Outlook limits?
No. Mobile uses illustrative budgets of 18 sender, 35 subject and 50 preheader characters; desktop uses 25, 60 and 100. Real visibility depends on client, font, viewport and layout. The presets help editing rather than certify client-specific rendering.
Can I use my own character limits?
Yes. Enter whole-number overrides from 1 to 500 for any field, leaving other overrides blank to retain the preset. Use a deliberate editorial constraint from your own testing. An override is still a text budget rather than a prediction of inbox pixels.
How are combined emoji counted?
Where Intl.Segmenter is available, visible grapheme clusters are counted separately from Unicode code points. A family emoji or accented letter may therefore count as one visible cluster despite several code points. Browsers without that support use code points and show a limitation note.
Do spaces and line breaks count?
The preview collapses whitespace sequences into single spaces and trims the ends before counting. Tabs and line breaks trigger review notes because the approximation displays them as spaces. The count describes normalized preview text, not the original raw input’s length.
Why is an ellipsis shown beyond the chosen budget?
The ellipsis is a display marker indicating truncation. It is outside the content budget, so it does not reduce the number of retained content characters. Actual clients can use different truncation and wrapping behavior, which this approximation does not simulate.
What happens if I leave the preheader blank?
The tool flags the empty field. An email client may pull text from the beginning of the body instead, depending on the final message implementation. Set intentional preview text in your sending platform and test it to avoid an unhelpful body excerpt.
Will this predict open rates or detect spam wording?
No. It checks text structure, budgets and repetition, without sending an email or assessing deliverability. Use actual audience testing and your own reporting to compare message performance. A short subject can still be unclear, while a longer one can still communicate effectively.
Explore the topic in the blog
Sources and method
Use the references below to check definitions and platform guidance. The model’s scope and limits are explained above. Read our editorial standards.