Klaviyo Preview Text: Setup, Pitfalls and BFCM Use

Preview text appears in the inbox right after the subject line. Klaviyo describes what happens when you leave it empty: the mailbox pulls the first line of text from the body of the email, which can turn out to be an image's alt text or the navigation menu.

TL;DR. Without a setting, the mailbox picks the first line of the email body for you. In Klaviyo, the Preview text field is filled in at the subject line step, for a campaign as for a flow email, and it is only handled in drag-and-drop templates. The number of visible characters depends on the mailbox and the device. For a BFCM, this field extends the subject line of each calendar phase, and Klaviyo's A/B test lets you measure its presence against its absence.

Want an outside look before you schedule your sends? We offer a Q4 readiness audit: 30 minutes, free, no strings attached.

What Klaviyo says about preview text

The dedicated page presents preview text as one of the first things a recipient sees when an email arrives (Klaviyo, how to insert preview text into an email). It shows after the subject line and usually comes from the first line of text in the email body. Klaviyo cites two uses: summarize the email, or complement the subject line.

The point to watch comes from the next sentence on the page. If you do not insert preview text, mailboxes automatically take it from the first line of content, so an image's alt text or the navigation bar can end up there. Klaviyo concludes that it is best to specify exactly what the preview text should display.

Where to set it

In a flow email, the documented path is: open the flow, click the message to show the Email details sidebar, click Edit under Subject and sender, then fill in the Preview text field. In a campaign, you open the campaign, click Next, and the Preview text field is at that step (Klaviyo, how to insert preview text into an email).

Three editor limits appear on the same page.

• The feature is only supported in Klaviyo's drag-and-drop templates.
• For a custom HTML template, including one with drag-and-drop support, the person who designs the email has to insert the desired text at the very beginning of the code.
• For a text-only email, the very beginning of the email is used as preview text.

The field adds spacers automatically, so only the text you enter displays in the inbox. In our view, there is no need to pad the field with invisible characters to stop the start of the body from extending the line.

Visible length depends on the email client

Klaviyo notes that devices and mailboxes do not show the same number of characters, with smaller screens showing fewer. The page illustrates these limits with an image, and we reuse no figure from it. It advises keeping the text concise. The accessibility page, for its part, asks for preview text that is descriptive, enticing and short (Klaviyo, accessibility best practices).

In our view, a habit follows: put the most important words at the start of the text, check the mobile preview before scheduling, and treat the end of the sentence as a bonus.

A specific Gmail pitfall with numbers

The page points out that Gmail may remove commas inside a set of numbers in preview text: the example given turns 10,000 into 10000 in the preview. A text that contains an amount or a quantity can therefore display differently in Gmail. Check any amount written with a thousands separator in a test sent to a Gmail address before relying on it in a promotional send.

Displaying the preview text inside the email body

Klaviyo provides the tag {% render_variable preview_text %}, which reuses the text entered on the preview screen and can be pasted into any text block of the template. It lets you repeat, inside the email, the sentence that complements the subject line, without typing it twice.

Conversely, the page describes how to hide preview text entirely so that only the subject line shows in the inbox: you add an HTML block at the very top of the email, with a code snippet that Klaviyo provides and that pushes the content past the preview area. In our view, this choice is rarely justified for a BFCM campaign, because the preview area is one of the few free places to repeat the offer.

Ten subject line and preview pairings for a BFCM

The examples below are wordings we wrote. They do not come from the documentation and we attribute no result to them. The principle follows the two uses Klaviyo describes: the preview complements the subject line, or it summarizes the email. Square brackets mark what you replace. The phases are detailed in our article on 30 BFCM subject lines.

One rule applies to every line: a deadline, a stock level or a delivery time is only mentioned if the information is accurate at send time. That matches Klaviyo's warning on urgency, which it reserves for messages where it applies (Klaviyo, how to increase campaign open rates).

Testing the presence of preview text

The A/B test page lists preview text among the elements to test to improve opens, with one variation where it is present and one where it is absent (Klaviyo, how to A/B test an email campaign). The same page recommends changing one variable at a time and keeping the test to two variations. To test preview text, keep the same subject line in both variations. Open rate is the recommended winning metric, with a Klaviyo caveat about opens from Apple devices that use Mail Privacy Protection, which can inflate rates. Our guide to A/B testing in Klaviyo details the method.

Checklist before scheduling

1. The Preview text field is filled in for each campaign and each flow email concerned.
2. The template is a drag-and-drop template. For an HTML template, the text is inserted at the start of the code.
3. The important words come first, and the preview has been checked on mobile.
4. An amount written with a thousands separator has been checked in a Gmail test.
5. Deadlines, stock levels and discounts quoted are accurate at send time.
6. If you A/B test the preview text, the subject line is identical in both variations.

FAQ

What happens if I do not set any preview text?

The mailbox automatically pulls the first line of text from the email body. Klaviyo notes that an image's alt text or the navigation bar can then show up in that spot.

Does the Preview text field work in every template?

No. The feature is only supported in drag-and-drop templates. For custom HTML, the text is inserted at the start of the code, and for a text-only email, the start of the email serves as the preview.

How many characters are displayed?

It depends on the mailbox and the device, with smaller screens showing fewer. Klaviyo advises concise text and gives no single figure in the text of the page.

Can the preview text be reused in the email body?

Yes, with the {% render_variable preview_text %} tag pasted into a text block.

Can the preview text be removed?

Yes, with an HTML block placed at the very top of the email, following the page's procedure. In our view, for a promotional campaign, the preview area is usually better used to complement the subject line.

Want an outside look at your sends? We run Q4 readiness audits, or you can talk to the Deliver team directly.