There’s nothing worse than having image rendering issues in your email marketing.

Whether it obliterates the screen or is too tiny to see, an image that has been improperly sized can ruin an otherwise killer email campaign. Most email marketers aren’t even sure what they did wrong to cause this image-rendering disaster.

If you’re a part of this crowd, we’ve got you covered.

This short guide explains proper email marketing image sizes and best practices for using them in your email service provider.

It’s a nifty how-to, keeping you in the know… and your emails looking sharp.

Email marketing image sizes: Best practices

Before you upload an image to your ESP’s server, stop. Make sure the image is sized correctly for the space it will be filling in your email template.

Let’s say the area in your template supports a 600 x 200 pixel image.

Whatever image you’ve chosen to upload into that area should be sized to 600 x 200 pixels before uploading (with one exception noted below).

There are three other boxes you have to check before uploading.

1. Your image must be saved as one of three file types: .jpeg, .png or .gif format.

2. Your image file size must be under the max recommended size of 100 KB.

3. When using animated gifs, make sure you’re following these specific guidelines.

Simple, right?

Just a few steps, and you’re guaranteed perfect email marketing image sizes.

Pro tip: For the best experience on a retina display, double the size of your image. For instance, if you have a 640 px header graphic, upload a 1280 px version.

Wrong image size = bad news

So what happens if you don’t take the time to get your email marketing image sizes right? Things could go wonky for your subscribers.

First, your email might not even get to where it’s going if the image file size is too large. The larger the image size (over 100KB), the greater the chance an email filter or firewall will block the image entirely.

Imagine your subscribers excitedly opening your email like a package on Christmas morning only to find NO IMAGE. It’s a little awkward, to say the least.

And even if your email does get delivered — and subscribers are able to see the image — there’s a good chance it could load at the wrong size and break your layout. Not good.

Another issue to keep in mind is some servers reject or filter email marketing if the content is too image-heavy. That means no more slapdash email marketing campaigns where you throw in a bunch of images and don’t dedicate time to thoughtful design.

Every email marketing campaign needs to include a balance of text and images. And if you choose to resize those images once they’re uploaded into the server — instead of before — you’re going to run into trouble.

It takes time to download oversized images in an email. And on mobile devices, time is money… literally.

Downloading on a mobile device eats up precious data, and we all known how grumpy people get when their data is used up. Even if subscribers are on Wifi, a slow connection could mean the image may not display at all.

Pick any of these situations — they’re all frustrating for the subscribers and bad news for your email marketing program.

Conclusion: Easy image resizing

It’s of the utmost important you take email marketing image sizes seriously. That’s because most ESPs limit image size (including us), so you have no choice but to take the time to make sure everything is correct.

You can resize your images in a snap using image-editing tools such as ImageOptim, Caesium, or even Canva.

If you’re a WhatCounts customer who wants to dive a little deeper into proper image sizing, you can reach out to your customer success manager. And if you’re not a client, but need training or clarification for image rendering or email design, just reach out to our friendly team of email marketing experts. We’re happy to help!