Does the size of email images affect open rate or click-through?

Hi @ScottCodes, 

Ah, my apologies - I think I misunderstood your original question. The image size of a graphic does not impact the size of an email, but that doesn’t mean that the size of the image does not impact the load speed. There’s another post in the Community where @mkprkr and I address how the load time and image size are correlated. Per the details below, I was wrong to say that you shouldn’t try to optimize the size of your image to increase load speed.

Here’s the answer I shared, for easy accessibility: 

It sounds like currently, the emails you are sending with Klaviyo take a long time to load images, and you’d like to know what the reason could be?

As @mkprkr points out, generally the images you see in an email are actually links to an external URL where the images are located. When an email is sent out through Klaviyo, the browser is the one who loads the images; Klaviyo only sends the location of the image via the URL. Therefore, if you have detected that the images are loading slower, it is highly unlikely that the source of the problem is Klaviyo.

To add to this, some ways to mitigate this could be to reduce the size of your image (but don’t reduce it so much that it loses the quality!). In this blog post on 5 Rules for Using Images in Your Email Templates, it’s highlighted that: 

the larger your images are, the longer they’re going to take email clients to load. A long load time can be the difference between someone reading or ignoring your email. People are impatient — Kissmetrics reports that 40% of web visitors will abandon a page if it takes more than 3 seconds to load, and the same is true of email load times.

To make sure your emails don’t load too slowly, test them using a service like Litmus’s Image Check.

In fact, you can even resize an image directly in the Image Block editor. More details and tutorials on that here.