A Complete Guide to Optimizing Images in WordPress

December 14, 2016

Incorporating imagery into your WordPress page and post content is a critical part of creating an engaging experience for your website’s visitors. Images create visual stimuli for a call to action and enhance your website’s appearance, setting the tone and brand of your entire site.

Yet for some reason, one of the most common overlooked parts of WordPress SEO is image optimization. If you’re not cautious, images can bog down your site. Large images result in increased page load times and can account for over half of your site’s total size.

The Impact Images Have on SEO

Sure, Google understands that images add quality to your content and therefore reward you with a better ranking. However, they also understand that nobody likes a website that takes ages to load, therefore slow loading pages will negatively impact your SEO score.

Surely this seems counterintuitive. We need images to enhance our content and keep our users engaged, which we’re rewarded for; however, our images are large files that potentially slow down our site, which we’re punished for. What the heck, Google?

Well, that’s not necessarily the case. There’s something called image optimization and it is our best friend when it comes to finding the right “SEO balance” we’re seeking. A well-ranked site requires both the optimization of images to promote its ranking as well as optimization of images and image sizes to improve page speed and faster load times. In this guide, we’ll discuss how to optimize images for WordPress SEO.

How to Optimize Images in WordPress

If you want to optimize your images for WordPress SEO, you need to take into consideration the file type, image size, and dimensions. In addition, adding the right types of markers to images, such as writing good alt tags, title tags, and captions alongside proper placement and positioning of your images can earn you even more SEO brownie points.

File Type

Nearly all images on the Internet are either in the PNG, JPEG, or GIF file format. While all are acceptable, there are certain cases where you may want to save a file in one format over the over. Unfortunately, people often choose the wrong file type when saving their images for upload, which results in an unnecessarily large file size or poor quality image. If you choose the right file type, you can keep your pictures crisp without slowing down your site.

For example, a PNG file preserves the original image’s quality, which is great for logos and graphics; however, if you are working with a high-quality photo, saving it as a PNG will result in a large file size. Therefore, to reduce the file size of photos you should save them as a JPEG. As a rule of thumb, stick to the following rules:

  • JPEG – Use for photographs of people, places, or things as well as designs with a lot of colors. Avoid using on screenshots and text/graphics
  • PNG – Use for text/graphics, logos, screenshots, or when you need to keep the background transparent. Text and graphic images will look clean, but be cautious with regard to file size.
  • GIF – Use for short animated images or flat images with no gradients

Image Dimensions

A common issue that most WordPress users make is that they do not format the size of their images properly prior to uploading them. When you upload an image that is especially large, WordPress will format and edit the image to align with the dimensions of your site; however, it doesn’t compress the image.

Large image files drag down your site’s load time, which negatively affects your ranking on search engines. The solution: reduce the image file size by adjusting the image dimensions to the correct size. For example, at Planet WP we format our pictures to the size of the post’s width, which is roughly 600 pixels, prior to uploading it into WordPress.

If you’re using a Mac, it’s easy to resize your images. Just open the picture in Preview, navigate to Tools then select Adjust Size. Alternatively, if you’re on a Windows PC, open the picture using Paint and click the Image Menu at the top and select Stretch/Skew Image (or under the Image group on the Home tab, click the Resize button).

If you want more editing options and don’t have access to an image editing software application, such as Photoshop or Illustrator, you can always edit your images online for free through Pixlr or download a free image editor such as GIMP.

Image File Name

It’s best that you always name your file appropriately. For example, if you’re uploading a picture of a planet, the image name shouldn’t be pwp2017.jpg, but rather planet-venus.jpg. Shoot for the main keyword in the article as the first word of the image file name.

Image Tag Attributes and Captions

Image attributes, such as the alt tag, title tag and caption, strengthen the message toward search engine spiders. When uploading an image through the media uploader, WordPress provides you with the ability to add an alt tag, title tag, and caption for the image.

What are alt tags and title tags?

The alt tag describes what’s on an image and the function the of the image. It is predominately used by screen readers for the visually impaired to accurately describe what the image is; however it also describes the picture for search engines. As such, all images should have alt tags.

SEO trick: Include one of your page or post’s target keywords in the alt tag. This will help the image rank well for the keyword during an image search. Also, don’t stuff a bunch of words in attempt to trick search engines, Google will notice your shenanigans and flag it is spammy.

The title tag is a function that displays the title of an image when you hover your mouse over the image. This may improve the user experience; however, it does not have an impact on search rankings since search spiders don’t recognize them. Nevertheless, it’s right there in your WordPress panel so you might as well add one.


The last and final SEO element to image optimization is adding a caption. The caption is the text that accompanies the image and is important for SEO since it is recognized by search spiders. According to studies, captions under images are read on average 300% more than the body copy itself; as such, you should consider using them otherwise you may be missing out on the opportunity to engage your audience.

Wrap Up

Those who implement image optimization techniques properly stand to gain a significant amount of organic traffic in the long. While it can be mundane at times, image optimization is not a difficult task, especially considering the functions and features available from within the WordPress media uploader tool. If you’re brand new to WordPress and want to learn how to upload images, check out our Adding Images in WordPress video tutorial.

For more on SEO tips and tricks, check out our Beginner’s Guide to WordPress SEO.

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