When designing a new email template in Klaviyo, you will notice that the default width of every template is 600px.
While you can adjust this default setting, we don't recommend increasing the width of your template unless this is required for a more advanced layout. If you adjust the width above 600px we also recommend conducting robust testing around how your email will look across different email clients and devices.
Understanding Email Width
When you're designing an email in Klaviyo, the established width of your template creates the frame for your email content. Any content you add into your template should fit within this frame.
The 600px email width has become an "industry standard" in email marketing because historically, the average size of a viewport in all popular desktop email clients was between 500-600px. The "viewport" is the framed area on a display screen where a recipient will read your email. By setting the width of your email to 600px, you can ensure that, for the average viewport size, your recipients won't have to do a lot of horizontal scrolling to see all of your content.
The standard for 600px-wide emails has stuck around, and remains common today, even as optimizing emails across different devices (such as mobile) becomes increasingly important. Klaviyo works hard to give our customers "the best of both worlds" -- we highly recommend designing your emails at a width of 600px so they look great on desktop clients, and then we'll do the hard work to render your emails such that they're responsive across smaller screens (such as mobile devices) as well.
Note, however, that sticking with a 600px width will help optimize emails built with Klaviyo for mobile viewing. Emails designed to be much wider have a higher potential to look skewed when scaled down on a mobile device unless the email was carefully designed and optimized for this. This is why we encourage you to avoid increasing your template width beyond 600px unless you have a designer and/or other dedicated resources to optimize your layout across clients/devices.
Template Content and Set Email Width
As mentioned above, the established width of your template creates the frame for your email content. While you can manually ensure that all content you add into your template has a maximum width that fits within your email's established frame, Klaviyo will also take care of this for you as you add content into your template.
Klaviyo will automatically scale down images, with the aspect ratio preserved, and otherwise limit the width of all blocks so they never extend past the set width of the template itself. This means as you add images into your template, or build a table with multiple columns, you will see that all blocks remain constrained by your template's email width.
If you are adding custom code into template blocks, make sure you are taking into consideration the set width in your template's Style settings. The established email width in your Style settings will impact the rendering of all template blocks, even those with custom code that may attempt to set a different, larger width.