How to Use Screaming Frog to Audit Your Website Images


In addition to being the best-named SEO tool in existence, Screaming Frog has an incredible number of uses for anyone who manages a website. From deep, nuanced technical analysis to quick wins like finding images that slow down your site, Screaming Frog is versatile and can be used at a basic level by almost anyone. Best of all, it has a free version that can crawl up to 500 pages on any site. 

My focus today is on how to use Screaming Frog to crawl your website’s images, identify image file sizes that are too large, and then optimize them to improve your site’s performance. Before I do that, let’s quickly cover why faster images are good for both your users and Google’s robots.

Why image compression matters for SEO

Google has clearly established that it’s placed more emphasis on page speed in its results. July of 2018 marked the official rollout of the algorithm that prioritized page speed.

The primary reason? Google switched to mobile-first indexing in its search results in 2018 and it wants Google users to have a good experience. That means surfacing mobile-friendly pages that load quickly on any device. 

How to boost page speed with faster images 

With all of that comes page speed. There are nearly endless ways to improve page speed, many of which are complex and technical. However, in this post I’m focused on images and how they affect your site’s speed and performance.

For many websites, the biggest drain on speed comes from image weight. Even a few poorly-optimized images can cause a webpage’s total size to be several times what it should be. As a general rule, I try to size and compress images to be under 100 kilobytes, which is doable for most files while still retaining solid quality. I’ll get into how to compress images a bit later in the post.

How to audit images with Screaming Frog

Finding all of the images on your site with Screaming Frog takes just a few steps once you’ve downloaded the software.

First, enter your site address in the URL tool. Hit “Start” and the spider will run a crawl of your site. Once it finishes, just select the “Images” tab at the top of the screen. (Side note: the image below gives an idea of everything else Screaming Frog can do for you. I’ll reiterate: It’s an amazingly helpful tool.)

Image of Screaming Frog SEO tool.

From here, you can sort by image size to get a quick idea of the problem areas. Typically, I like to use the “Bulk Export > Images” feature here to get everything into a single spreadsheet. If your site is very large and you have a lot of images, you can deal with them in chunks. For example, here is a recent pull of a current client’s site.

Image of Screaming Frog image crawl, sorted by file size.

You can see there were a handful of major problem images that were really weighing down the pages they were on, including a few images that were pushing a gigabyte in size (!). I tackled these in bits, focusing on the largest images on the highest-trafficked, most critical pages of their site.

Compressing your images

Once you identify the key images on your site that need to be compressed, there are a few options to make them faster. You can either download the images from your site directly from the live page, or out of your website’s CMS. Some content-management systems even have an “overwrite” feature that makes this process even simpler. Regardless, create a folder on your desktop to store all of the images so they’re in one spot and clearly organized.

Before you use a compression tool, check to see if the images dimensions can be reduced. Often, website owners upload images to a content management system at full size, which can be several thousand pixels. They’ll then be displayed at a crunched-down size but that still requires a download of the full-resolution image. If you can upload an image at the size it’ll be displayed, that’s usually an immediate space-saver.

After you know your images are properly sized, you can use TinyPNG to compress them. TinyPNG works by stripping out unnecessary info and details from a photo, significantly reducing its size and making no noticeable difference in visual quality. For most web uses, there’s little reason to have large, high-resolution images slowing down page load.

You can drag up to 20 images at a time into TinyPNG. Each one will compress in a few seconds and offer a “download” link that will pull your new, beautifully compressed image onto your machine. From there, just upload the new file to your CMS.

Another image compression tool I like it Squoosh, which lets you get a side-by-side comparison of image quality. It offers a slider you can drag up or down to see how size reduction impacts the visual quality.

Improve page speed because it’s good for your users

So with that, you now have a list of problematic images on your site and a toolbox you can use to fix them.

When it comes down to it, your focus as a website owner should be on creating a good experience for your site visitors. So yes, having smaller, faster-loading images is great for your website’s search engine optimization. But it’s also great for your user’s experience on your site since they will spend less time waiting around for big images to load. Even a few seconds of load time can make the difference between a visitor staying on your page and bouncing away to another site that loads more quickly. According to Google itself, 40% of users will leave a page if it takes longer than three seconds to load.

If you have any questions about how to compress images, I’d always be happy to answer them. Feel free to get in touch.

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