This article explains what impacts email size, why it matters, and how you can optimize your emails for better performance.

Emails are built using HTML, similar to webpages. Like webpages, they load assets such as images and fonts. Unlike webpages, however, some email clients impose limits on the size of the HTML code.

Email file size

Email size has two parts:

• Email code weight - The size of the email’s code. This means HTML tables, text, links, and similar elements.
• Downloaded email weight - Everything your reader must download in order to render the email, including the HTML file and all its assets such as images and custom fonts.

When people refer to “email size”, they usually mean email code weight, not the total downloaded weight.

Large images, many images, uncompressed assets, custom fonts, large HTML code, and animated GIFs all increase file size and can slow down loading.

Why it matters

Email messages with high downloading weight can:

• Load slowly or only partially render.
• Hurt the user experience and reduce engagement.

Gmail clips emails when the HTML exceeds ~102kb. 

This can result in:

• The message being cut off behind View entire message

• Styling issues when expanded

• Tracking pixels not firing

• Footer content (including unsubscribe links) being hidden

• Reduced engagement

Deliverability

Email size alone does not directly impact deliverability.

However, large emails can lead to slower loading or clipping, which reduces engagement. Over time, lower engagement can negatively affect deliverability.

As a best practice, aim to keep email code weight under 80kb when possible.

Large email → Clipping or slower render → Lower engagement → Long-term deliverability decline

Practical tips

Measure your email size using tools like Litmus or About My Email.

To reduce file size and improve performance:

• Compress images or reduce the number of images

• Optimize or reduce frames in animated GIFs

• Use web-safe fonts (e.g. Arial, Verdana, Georgia, Times New Roman)

• Avoid duplicating large blocks of code

A number of factors can influence email file size, including:

• Length of email
• Too many modules
• Too many images
• Large image sizes
• Uncompressed images
• Animated GIFs
• Coding style
• Custom fonts
• Length of file names

How to optimize

Keep your emails simple:

• Use padding instead of spacer elements

• Minimize repeated structures

• Use grid-based layouts for more complex sections like footers

Examples

Rows example 1 - 15.9kb

Text elements are placed on separate rows and columns. This is not recommended because it creates extra code that is not needed.

Rows example 2 - 10.6kb (-5.3kb)

Text elements are instead placed in the same column for the same result, but with less code. This small edit saves 5.3kb and is also visually easier to work with in Design Studio.

Spacer example 1 - 11.4kb

You can use this element to create space in modules, but its usage should be limited since this option adds to the total weight of the email.

Spacer example 2 - 10.6kb (-0.8kb)

A better option is to use padding to create space between elements and modules. This gives the same result, with a small saving of 0.8kb. It sounds like a little, but across a whole email with several modules, it adds up.

Footer example 1 - 35.2kb

This module contains a lot of elements on different rows and columns. Even though it is a common module, it is easy to make it heavy.

Footer example 2 - 26.3kb (-8.9kb)

You can create the same solution using the Grid element. With this, you do not need the Wrapper element.

Article last reviewed 18 March 2026 09:17