How to Eliminate Unused CSS and JS from WordPress: A Comprehensive Guide

In the world of web development and optimization, efficiency is the name of the game. One of the key aspects that developers and website owners often overlook is the existence of unused CSS and JS files within their WordPress sites. These files can significantly slow down your site’s loading speed and affect its overall performance. However, the good news is that this issue can be easily rectified with the right tools and techniques.

In this guide, we’ll take a deep dive into how you can remove unused CSS and JS from your WordPress website using a two-step process: identifying unused files with the coverage tool in Chrome’s DevTools, and then removing them using a WordPress plugin called Asset CleanUp.

Before we delve into the how-to, let’s go over some important statistics to underscore the importance of this topic.

The Impact of Unused CSS and JS Files

Every second counts when it comes to site loading speed. According to data from Google, 53% of mobile site visitors will leave a page that takes longer than three seconds to load. Furthermore, a one-second delay in page load time can lead to a 7% loss in conversions, 11% fewer page views, and a 16% decrease in customer satisfaction.

What’s more, the size of your website’s files directly impacts your site’s loading speed. The larger the file size, the longer it will take for your site to load. Unused CSS and JS files contribute to this file size, making your website slower.

Leveraging Chrome's DevTools: The Coverage Tool

Google Chrome’s DevTools provides developers with a plethora of tools for debugging and optimizing websites. One such tool is the Coverage Tool, which allows developers to identify unused CSS and JS code within their websites.

Step 1: Open Coverage Tool

Open Google Chrome and navigate to your WordPress website. Right-click anywhere on the page and select ‘Inspect’. This will open the DevTools panel. In the DevTools panel, click on the three dot button and then select ‘More Toos’ > ‘Coverage’.

How to Eliminate Unused CSS and JS from WordPress

Step 2: Start Capturing the Coverage

Click on the reload button (a round arrow) in the Coverage panel to start capturing the coverage. As your webpage reloads, the Coverage tool will track all the loaded CSS and JS files and identify the used and unused bytes of code.

How to Eliminate Unused CSS and JS from WordPress

Step 3: Analyze the Coverage Results

Once the page has loaded, the Coverage tool will display a list of all the CSS and JS files loaded by the page. Each file will have a bar next to it, showing the amount of used and unused code. Red indicates unused code, while green indicates used code. Clicking on a file will open it and highlight the unused code in red.
How to Eliminate Unused CSS and JS from WordPress

Removing Unused CSS and JS with Asset CleanUp

Once you’ve identified the unused CSS and JS files, it’s time to remove them. This is where the Asset CleanUp WordPress plugin comes into play.

Step 4: Install and Activate Asset CleanUp

Log in to your WordPress admin panel. Navigate to ‘Plugins > Add New’, search for ‘Asset CleanUp’, install, and then activate it.

How to Eliminate Unused CSS and JS from WordPress

Step 5: Configure Asset CleanUp

After activation, go to ‘Settings > Asset CleanUp’. Here, you can configure the plugin based on your needs. For beginners, the default settings should be fine.

Step 6: Scan Your Pages

Go to ‘Asset CleanUp > CSS/JS Manager’. Here, you can choose to scan all your pages or select specific pages to scan for unused CSS and JS files. After selecting your pages, click on ‘Start Scanning’.

How to Eliminate Unused CSS and JS from WordPress

Step 7: Review and Remove Unused Assets

Once the scan is complete, Asset CleanUp will list all the CSS and JS files loaded by your scanned pages. Here, you can review each file and decide whether to keep it or unload it. To unload a file, simply click on the ‘Unload’ button next to it.

How to Eliminate Unused CSS and JS from WordPress

Step 8: Test Your Website

After removing the unused assets, make sure to test your website thoroughly. Ensure that everything still works as expected and that you didn’t accidentally remove any necessary files.


Keeping your website lean and efficient by removing unused CSS and JS files is a crucial part of website optimization. It not only improves your site’s loading speed but also enhances your users’ experience and your site’s SEO performance. The process might seem daunting at first, but with tools like Chrome’s Coverage and the Asset CleanUp plugin, it becomes a manageable and rewarding task.

Remember, in the digital world, every second counts. So, start cleaning up your WordPress website today and provide your visitors with the fast, efficient experience they deserve.

Please note that manual removal of unused CSS and JS can be complex and time-consuming. It’s recommended to take backups and proceed with caution. If you’re unsure, consider hiring a professional developer.