How to Remove Unused CSS from WordPress

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Anyone who sells goods online knows conversion rate is a critical success metric. However, for many small ecommerce business owners, optimization can be tricky. One of the most significant contributors to conversion is the user experience. If site visitors can quickly access and easily navigate your site, you’re off to a good start. However, many things can create a bad experience for your potential customers. 

Pages that load slowly turn potential customers off. The longer a page takes to load, the more visitors leave your site. That is not ideal for any ecommerce business – after all, the whole point is to bring in traffic and then solve a problem for them with your products and services. 

While there are many ways to increase your conversion rate. Today, we’re going to talk about the impact unused CSS can have on page performance and how to remove unused CSS from WordPress. 

Keep reading for information on how to remove unused CSS from WordPress.

What Is “Unused” CSS?

Simply put, Cascading Style Sheet, or CSS for short, is a type of language used to present a website in a common language such as HTML.

Sounds confusing, right?

While the jargon may make you scratch your head, CSS is the language used to design your WordPress website’s theme. 

When creating a theme for a website, developers often write the themes so that most sites can support the theme. 

These sites require different types of HTML elements like: 

  • Icons 
  • Tables 
  • Typography 
  • Widgets 
  • Search bar 
  • Social media buttons 

And so on and so forth. This information is usually saved in a file called style.css. Whether these elements are used or not, all of the CSS is served to your users. They can end up slowing down your ecommerce site speed. This is why it’s called unused CSS.

“You’re building unnecessary complexity into your site to sell a product. The question I ask our clients is if the functionality is required for your business. If not, simplify your site.” – Patrick.

If these site elements don’t provide value to your audience, then they need to go. 

Removing unused CSS should improve loading speeds but doing so can be challenging. 

Before diving into the nuts and bolts of how to remove unused CSS from WordPress, it’s essential to distinguish the different types of unused CSS.

Types of Unused CSS

Unused CSS belongs in two categories:

  • Non-Critical CSS
  • Dead CSS

Both types of unused CSS can cause slow load times. 

Non-critical CSS is any CSS that doesn’t render what is called above-the-fold content. Essentially, above-the-fold content is what a potential customer first sees on your website without scrolling.

Non-critical CSS can still be used on other pages as well as content below-the-fold.

Dead CSS, on the other hand, refers to any CSS that isn’t used anymore. This could include CSS leftover from previous site versions or other temporary uses.

How Does Unused CSS Affect Your Website 

Page Performance

It’s no secret that unused CSS can affect a website’s loading time. Essentially, some CSS must be rendered before a website loads. When your WordPress site is filled with unused CSS, this takes up precious seconds of loading time. 

All of this adds up to user frustration and lack of customer conversions.

What is an Ideal Load Page Time?

Generally, an ideal load page time should be less than four seconds. Anything above that, especially above six seconds, is less than optimal.

Why is Page Load Time So Important?

A slow load time for a website can affect a merchant’s conversion rate for their ecommerce website. On average, an ecommerce website can lose up to 40% of its potential customers when their load time is longer than three seconds.

Data from Hubspot

In addition to losing customers, this can affect your website’s ranking in popular search engines. This is why optimizing your website for better customer conversion rates is critical if you want your ecommerce business to succeed.

This is why boosting your ecommerce website for optimal conversion rates is so critical. One component of this is removing unused CSS.

How to Remove Unused CSS from WordPress

While unused CSS isn’t the end of the world, it could spell trouble for your conversion rate optimization. However, there are some options available.

Why is Removing Unused CSS Difficult?

Unfortunately, removing unused CSS can be very difficult. Plugins can contribute to above-the-fold critical CSS. There also may be JavaScript files that add CSS codes. These can be based on various actions such as button clicks.

Identifying critical and non-critical CSS can be tricky, especially if you are inexperienced in doing so.

Trouble with Dynamic Classes

These dynamic CSS classes can often prove difficult to extract. This is because the CSS classes are located inside the JavaScript files. This makes finding the class names extremely hard.


Code-splitting is one way of identifying unused CSS. This method can seem quite complicated but essentially is splitting code into small groups and then inserting the necessary files into your WordPress website.

This method can be accomplished via manual entry or with the use of plugins.

Best Tools and Practices To Remove Unused CSS

While removing all CSS files on your ecommerce website can be almost impossible, there are a few ways to reduce them.

Analyzing Unused CSS

After code-splitting the large CSS files, the next step is to analyze unused CSS. You can do this by using a browser’s developer tool.

Depending on which browser you use, you should open their devtool and generate a report that shows used and used code. The rest is as simple as highlighting and removing all unused CSS files.

Removing Unused CSS with AssetCleanup Plugin

Another way to remove unused code is with the AssetCleanup Plugin. With this plugin, you can scan your ecommerce page for any unused CSS.

AssetCleanup includes an unload feature that enables you to remove unused CSS files. This can be as simple as clicking on highlighted CSS files and turning them off.

Critical CSS Generation

An alternative method for how to remove unused CSS from WordPress is generating critical CSS. Critical CSS is any CSS used to display above-the-fold content on your ecommerce site. Various plugins can accomplish this.

The benefit of generating critical CSS is that it can be as easy as clicking a button.

CSS Delivery via CDN

Finally, boost your conversion rate optimization for ecommerce is by using a content delivery network.

Commonly referred to as a CDN, these networks improve load times for CSS files. It is important to note that a CDN does not host your website’s content but instead helps cache content. This leads to improved, optimized load times.

Key Takeaways

When it comes to removing unused CSS from your WordPress website, the process can be complicated. Fortunately, you’re not without hope.

Mindsize is an agency that specializes in helping your ecommerce website reach its full potential.

Founded in 2017, Midsize offers affordable services in boosting your conversion rate optimization for ecommerce. This includes building a custom ecommerce website on WordPress as well as providing consultation services for existing sites.

While the technical aspects of improving your website’s load time may seem daunting, removing unused CSS from your WordPress website with Mindsize couldn’t be simpler.

Sign up for a performance audit and our team of experts will let you know exactly where you can make changes.