Email preview text (preheader) checker

Put the words that matter first. For the example email (a 40-character subject line), this is how much of the preview text each screen shows:

How we measure: each screen is drawn at its real size (an iPhone screen is 390 by 844 points; Gmail on a laptop is a 1280-pixel-wide window) in the fonts those apps use, and the tool counts how many characters fit before the app cuts them off. Your phone model and text size setting can move it by a few characters. Measured 16 October 2026.

So the first 40 or so characters are the ones nearly everyone sees. On a laptop the subject line and the preview text share one line, so a long subject leaves less room for the preview.

Preview text is the grey line after the subject line in an inbox, and the line under the subject in a phone notification. Email tools often call it a preheader: it’s the same thing. It’s the second thing people read, after your name and subject line, and it often decides whether they open.

In a plain-text email, Gmail takes the first words of the email. In a designed email you can set the preview text yourself, usually in a “preview text” field in your email tool. If you don’t, Gmail grabs whatever text comes first, which is sometimes “View this email in your browser”.

Use your email tool’s preview text field if it has one. If you write the HTML yourself, put a hidden line at the very top of the body:

<div style="display:none;max-height:0;overflow:hidden;">Your preview text here</div>