How to Minify JavaScript and CSS in WordPress: Boost Speed & SEO with Plugins or Manual Methods

Do you want your WordPress website to load faster and rank higher in Google? Minifying JavaScript and CSS files is one of the easiest ways to speed up your site, improve user experience, and boost SEO.

Website performance plays a huge role in user experience and search engine visibility.

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Google considers website speed as a ranking factor, so optimizing your CSS and JavaScript can directly impact your search rankings and conversions.

Besides enabling caching and using a CDN provider, there is a simple optimization method that can help you reduce the size of static files and improve loading speed.

That’s called minification.

Minification works by removing unnecessary spaces, line breaks, and comments from your code, which makes your files smaller and your pages quicker to load.

In this step-by-step guide, you’ll learn:

• What minification is and why it’s important
• How to check if your files are already minified
• The best plugins and manual methods for minifying CSS and JS in WordPress
• How minification compares to caching and compression

Let’s get started optimizing your WordPress site for speed and better search performance.

First, let’s see what minification is and why you should use it.

What is Minification?

Minification is the process of removing unnecessary spaces, line breaks, comments, and formatting from JavaScript and CSS files. This reduces file size, speeds up loading times, and improves page performance without affecting how the code works.

Why You Should Minify JavaScript and CSS?

By minifying CSS and JavaScript files in WordPress, you can significantly enhance page load speed and overall site performance by reducing file sizes.

This optimization improves your Largest Contentful Paint and other essential Core Web Vitals metrics.

For example, an original, unoptimized CSS code will look like the following code. The total size of this unminified CSS is 545 bytes.

/* Main container styles */
.container {
width: 100%;
max-width: 1200px;
margin: 0 auto;
padding: 20px;
}

/* Header styles */
.header {
background-color: #f8f8f8;
color: #333;
font-size: 24px;
text-align: center;
padding: 15px 0;
}

/* Navigation menu */
.nav-menu {
list-style-type: none;
padding: 0;
margin: 0;
display: flex;
justify-content: center;
gap: 20px;
}

/* Navigation links */
.nav-menu li a {
text-decoration: none;
color: #007bff;
font-weight: bold;
}

.nav-menu li a:hover {
color: #0056b3;
}

Now, the minified CSS version of the same code is reduced by 35%, totaling just 354 bytes.

.container{width:100%;max-width:1200px;margin:0 auto;padding:20px}.header{background-color:#f8f8f8;color:#333;font-size:24px;text-align:center;padding:15px 0}.nav-menu{list-style-type:none;padding:0;margin:0;display:flex;justify-content:center;gap:20px}.nav-menu li a{text-decoration:none;color:#007bff;font-weight:bold}.nav-menu li a:hover{color:#0056b3}

As you can see, with a minification plugin or any minification tools, you can easily remove all unnecessary elements from the code, which can significantly reduce the JavaScript or CSS file size by as much as 25-90%.

In this case, the CSS file size is decreased by 35%.

Now you have an idea of what minification is and why you should use it.

How to Check If Your JavaScript and CSS Are Minified

1. Go to Google PageSpeed Insights.
2. Enter your website URL and click Analyze.
3. In the results, look for “Minify CSS” or “Minify JavaScript” under Opportunities.
4. If you see “Passed”, your files are already minified.

Once you have added the minification feature to your WordPress website or WooCommerce store, it is mandatory to test if it is working correctly.

While you may not be able to spot the difference naturally, it is ideal to use third-party tools like Google PageSpeed Insights or GTmetrix.

Below, I will show you how to use these tools to verify whether your minified JavaScript and CSS are actually minified.

Google PageSpeed Insights

Google PageSpeed Insights is an excellent tool used for evaluating a website’s speed and performance.

For this example, I am testing my site on the Google PageSpeed Insights tool to check if the CSS and JS are minified.

Go to Google PageSpeed Insights and enter the address. Once you are done, click Analyze.

Here, I am using PageSpeed Insights to analyze my site, https://technumero.com, for JavaScript and CSS minification. Take a look at the outcomes below:

Now you need to go to the audits section, and there you will see the results.

As you can see in the screenshot that minification of JS and CSS files is already enabled.

Next, let’s see how to use GTmetrix for testing the minification.

GTmetrix

The first thing you need to do is go to GTmetrix. There, enter the website’s address and click ‘Test Now‘.

I am testing my site on GTmetrix, see the results below:

Within a short time, you can see the results. Go to the structure tab.

Scroll down to view the results of both CSS and JavaScript modifications.

Step-by-Step: How to Minify JS and CSS for WordPress Speed Optimization

There are two methods you can use to implement JavaScript and CSS minification:

• Using a dedicated plugin
• Do it manually, without a plugin

Below, I will outline both methods so you can choose one according to your preferences.

How to Minify CSS and JS in WordPress With a Plugin

If you are looking for a simple method, go for the plugin method. Even Google PageSpeed recommends using a WordPress plugin to minify CSS or JavaScript files.

There are multiple plugins (both caching and performance optimization) that can help you minify the static files. Here, I will recommend a few and also show how to use them for minification.

• FlyingPress
• Perfmatters
• Auptomize
• WP Fastest Cache
• W3 Total Cache

1. FlyingPress

I use the FlyingPress plugin on my site, https://technumero.com, to minify JS and CSS files.

Let’s see how to use the FlyingPress caching plugin for minification. Once you have activated the plugin, open the plugin settings.

On the left-hand side, you can see the CSS and JavaScript optimization tabs.

You can open those and see the minification options.

1.1 JavaScript Minification

1.2 CSS Minification

To make the website even faster, you can consider enabling the ‘Remove Unused CSS‘ option, in addition to code minification.

Save settings after enabling minification.

2. Perfmatters

Perfmatters is another popular performance optimization plugin I am using for various optimizations on this site, including CSS and JS minification. So if you are a Perfmatters user, you can enable CSS and JS minification via the plugin settings.

2.1 JavaScript Minification

To enable JavaScript minification, open the JavaScript tab. There, you will see the option.

Save the settings after enabling it.

2.3 CSS Minification

The same goes for the CSS files.

Save the plugin’s settings once you are done with the options. It is one of the best WordPress plugins to minify CSS and JS.

3. Autoptimize

By default, Autoptimize comes with CSS and JS minification enabled. After activation, you can see the plugin’s settings under WordPress Settings.

There, you can check the JS and CSS minification options.

3.1 JavaScript Minification

3.2 CSS Minification

If they aren’t enabled, feel free to enable them and save the settings.

4. WP Fastest Cache

WP Fastest Cache makes it easy to enable minification on CSS and JS files. Once you have activated the plugin, go to the main settings page.

There, you will see the minification options, and that’s it.

4.1 JavaScript & CSS Minification

Enable those and save the settings.

5. W3 Total Cache

The last plugin I have for you is W3 Total Cache. After activation, you can see the minification option on the left-hand side.

From there, you can minify the static files.

5.1 JavaScript Minification

5.2 CSS Minification

Manual Minification in WordPress Without Plugins

You can optimize your site’s performance by manually minifying CSS and JS files using free online tools if you don’t want to use plugins.

There are so many online minification tools available that can help you optimize your files without using a third-party plugin.

Use a CDN for File Minification

Many Content Delivery Networks (CDNs) like Cloudflare offer automatic minification as part of their performance features. They minify JavaScript, CSS, and HTML files on the fly to reduce loading times globally.

Online JS and CSS compressor Tools

• JS Compressor for JavaScript Minification
  • Online JavaScript Minifier Tool
• CSS Compressor for CSS Minification
  • CSS Minifier
• CSS & JS Minification Scripts
  • YUI Compressor
  • js

For this tutorial, I will use the CSS Minifier tool. Open the tool, paste your raw CSS code, and click minify.

And if you scroll down, you can see the code you have generated via manual minification.

Similarly, you can utilize any available tools to optimize the CSS and JS files through minification.

Bonus: How to Minify HTML in WordPress

In addition to minifying JavaScript and CSS files, optimizing your HTML source code can improve site speed and overall web performance.

Minifying HTML means removing unnecessary spaces, line breaks, and comments from your code.

This helps reduce page load speed and improves metrics like Largest Contentful Paint. Most site owners prefer using a cache plugin to handle this task.

Tools like LiteSpeed Cache, WP Rocket, and Cache Enabler offer built-in features for HTML and JavaScript minification, as well as other techniques such as GZIP Compression and text compression.

Here, I will show you how you can use the LiteSpeed Cache WordPress plugin to Minify HTML.

Once you have activated the LiteSpeed Cache plugin, open the page optimization tab. There, you will see the option to enable HTML minification.

Enable that option and save the changes.

This will automatically compress your HTML files, clean up excess PHP code spacing, and prepare your website for faster delivery.

Combining HTML minification with optimized JavaScript libraries and server-side compression can lead to noticeable improvements in page speed.

What Is the Difference Between Minification and Compression?

Minification and compression are both used to make your website load faster, but they work differently.

• Minification removes unnecessary characters (like spaces, line breaks, and comments) from your JavaScript, CSS, or HTML files. The result is a smaller file with the same code and functionality, just without extra formatting.
• Compression (such as GZIP compression) takes your files, minified or not, and packs them into a smaller size for transfer over the internet. When a visitor loads your site, their browser automatically decompresses the files.

In summary, Minification makes your code files smaller by cleaning them up, while compression shrinks your files for faster transfer between your server and your visitors.

For best performance, I always recommend using both minification and compression together.

What Is the Difference Between Minification and Caching?

Minification and caching are both performance optimization techniques, but they serve different purposes.

Minification reduces file size by removing unnecessary characters like white spaces and comments from your JavaScript and CSS code.

Caching, on the other hand, stores a static version of your site so it loads faster for repeat visitors. While minification improves how quickly files are downloaded, caching speeds up how quickly pages are served to users.

Together, they significantly enhance load speed and overall site performance.

Frequently Asked Questions

Next, let’s see some frequently asked questions regarding the topic.

Conclusion

Minifying JavaScript and CSS files is a powerful yet simple step toward boosting your WordPress site’s performance.

By eliminating unnecessary characters like white spaces and line breaks, you can significantly reduce file size, improve load speed, and enhance overall user experience.

You can use a caching plugin/performance optimization plugin like FlyingPress, WP Rocket, W3 Total Cache, or Perfmatters for the process. Additionally, if you are using a LiteSpeed hosting server, I recommend you use the LiteSpeed Cache plugin for JS and CSS modification. Otherwise, you can use dedicated online minification tools for this task.

If you are using a CDN provider, they can also help you with minifying the static files. It should be a standard practice for every website to optimize the speed and reduce bandwidth usage.

WordPress speed optimization isn’t complete without JavaScript and CSS minification. Combine caching, CDN minification, and code optimization for best results with Google PageSpeed Insights and Core Web Vitals. For more tips on boosting site speed, read our guide on WordPress Caching Plugins.

So, the question is for you.

Which minification method will you be using to improve the site’s performance?

Let us know in the comments.