Real Testing Data: 5 Best Image Optimization Plugins Compared

/Real Testing Data: 5 Best Image Optimization Plugins Compared

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If you want to speed up your WordPress site, optimizing your images is one of the best steps you can take.

According to Akamai, the average website’s file size is 63% images. So if you’re not already optimizing your images, that means you probably have a ton of room for improvement when it comes to your pages’ file sizes!

In this post, I’m going to dig into 5 of the best WordPress image optimization plugins. Each of these plugins will automatically optimize every single image that you upload to your WordPress site, including those used in photo gallery plugins – you don’t need to think about a thing!

And to help you make your decision, I’m going to actually go hands-on and test each plugin to see how much it compresses both JPEG and PNG images. That way, you can make your decision based on cold hard data.

Keep reading to learn more about the plugins and check out the data!

How Do Image Optimization Plugins Work?

Most WordPress image optimization plugins let you perform two core functions. They might offer other smaller features, but generally it comes down to helping you:

  • Compress your images
  • Automatically resize image dimensions

While that seems pretty simple, there are a few differences in how those things happen that might make you choose one plugin over another.

First, there are two types of compression:

  • Lossy – huge file size reductions but at the expensive of some quality
  • Lossless – smaller file size reductions but no loss in quality

Some plugins only offer one type of compression in their free version, while others offer lossy and lossless for free.

Additionally, image optimization plugins differ in where that compression happens. Most plugins outsource the image compression to their own servers via API rather than doing it on the same server as your WordPress site. However, some do let you compress files on your own server.

Keep these distinctions in mind as you read through the list.

How I’ll Do This Image Optimization Plugin Comparison

Rather than simply listing each plugin’s features, I want to make this image optimization plugin comparison a little more scientific.

To do that, I’m going to run a real test to compare these plugins. For each plugin on this list, I’m going to upload and compress the same:

  • JPEG image
  • PNG image

That way, you’ll know exactly how effective each optimization plugin is.

This gets a little complicated because some plugins offer multiple levels of lossy compression. If I encounter that, I’m going to choose the highest available free compression level.

Keep reading to both learn more about the plugins and get a look at some real data!

Best WordPress Image Optimization Plugins: A Summary

If you just want a quick look at each image optimization plugin’s features, here’s a table summarizing what you’ll learn in this article. At the end of this article, I’ll also give you a similar summary table for my real testing data, so I encourage you to read this until the end!

Imagify

EWWW Image Optimizer

WP Smush

Compress JPEG & PNG images

ShortPixel

Lossless compression?

YES

YES

YES

NO

YES

Lossy compression?

YES

YES, but no JPEG in free version

YES, but only in paid version

YES

YES

Image resizing?

YES

YES

YES

YES

YES

Server-side or API?

API

BOTH

API

API

API

Bulk Optimize Old Images?

YES

YES

YES

YES

YES

1. Imagify

Overview

Imagify is a freemium image optimization plugin from WP Media, the same company behind the popular WP Rocket cache plugin.

Imagify gives you three levels of compression:

  • Normal – lossless compression
  • Aggressive – lossy compression but preserving as much quality as possible
  • Ultra – even more aggressive lossy compression

In addition, Imagify can also automatically resize images that you upload. And if you need to optimize a bunch of old images, Imagify lets you bulk optimize your entire media library with a single click.

All of this comes in a well-designed interface (as you’d expect from the makers of WP Rocket).

In order to use Imagify, you’ll need to sign up for a free Imagify account and connect your site to Imagify’s servers via API.

How It Performed In The Real-World Test

Remember – though Imagify offers multiple levels of lossy compression, I chose the highest “Ultra” level for this test.

JPEG Lossless Compression

JPEG Lossy Compression

PNG Lossless Compression

PNG Lossy Compression

Reduction in Size

4.39%

80.33%

32.01%

81.31%

Pricing

Imagify lets you optimize up to 25MB of images per month for free. After that, you’ll need to purchase credits starting at $4.99 per month for 1GB of data.

2. EWWW Image Optimizer

Overview

EWWW Image Optimizer is a free image optimization plugin, though there is an optional paid plan which offers API access and more compression options.

What’s fairly unique about EWWW Image Optimizer is that it lets you optimize your files on your own server instead of needing to outsource it to someone else’s server. This is helpful if:

  • You don’t want to outsource image optimization for privacy reasons
  • You don’t want to pay for an API service

The only downside is that the free version limits you to lossless compression for JPG files. You can compress PNG files both losslessly and lossily, though.

Other than that potential downside, EWWW Image Optimizer has everything else you need. That means:

  • Automatic image resizing
  • Bulk optimization for older images

How It Performed In The Real-World Test

JPEG Lossless Compression

JPEG Lossy Compression

PNG Lossless Compression

PNG Lossy Compression

Reduction in Size

4.1%

Not available

23.9%

68.6%

Pricing

If you use your own server, EWWW Image Optimizer is 100% free no matter how many images you optimize.

If you want to outsource your compression via API or get access to more compression algorithms, the paid plan starts at $0.003 per image.

3. WP Smush

Overview

WP Smush is a freemium image optimization plugin from WPMU DEV.

In the free version of the plugin, WP Smush optimizes all of your images with exclusively lossless compression. This optimization happens on WPMU DEV’s servers, rather than your own.

WP Smush also lets you:

  • Automatically resize images
  • Bulk optimize old images, though you can only compress 50 images at a time in the free version. So if you have thousands of old images, you’ll need to keep your clicking finger nimble.

There is one caveat about the free version, though:

It only works on images up to 1MB.

Other than that, there are no restrictions on the number of images you optimize, which is pretty generous.

How It Performed In The Real-World Test

JPEG Lossless Compression

JPEG Lossy Compression

PNG Lossless Compression

PNG Lossy Compression

Reduction in Size

4.9%

Not available

11.2%

Not available

Pricing

If you’re fine with lossless compression and a 1MB file size limit, you can use the free version for unlimited images.

If you want the Pro version, you’ll need to sign up for a WPMU DEV Membership, which will run you a cool $49 per month.

4. Compress JPEG & PNG images

Overview

Compress JPEG & PNG images doesn’t beat around the bush with its name! This plugin helps integrate your site with TinyJPG and TinyPNG via API for easy compression.

It works by automatically sending each image to the external TinyJPG or TinyPNG service. The plugin description says the compression happens “without visible loss in quality.”

But the file size reductions offered by the plugin are really only possible with lossy compression.

Like the other plugins, Compress JPEG & PNG images also offers:

  • Automatic image resizing
  • Bulk optimization for older images

How It Performed In The Real-World Test

JPEG Lossless Compression

JPEG Lossy Compression

PNG Lossless Compression

PNG Lossy Compression

Reduction in Size

Not available

39%

Not available

75%

Pricing

The plugin lets you optimize up to 500 images of any size per month. After that, you’ll need to pay somewhere between $0.002 to $0.009 per image to continue optimizing.

5. ShortPixel Image Optimizer

Overview

ShortPixel is a well-designed image optimization plugin that lets you both lossily and losslessly compress all of the images on your site. Like Imagify, you’ll need to sign up for a free ShortPixel account to get an API key in order to start using the plugin.

Beyond automatic image resizing and bulk optimization, ShortPixel has a few other neat features going for it:

  • Support for retina images
  • Glossy JPEG compression designed specifically for photographers
  • WebP support

How It Performed In The Real-World Test

JPEG Lossless Compression

JPEG Lossy Compression

PNG Lossless Compression

PNG Lossy Compression

Reduction in Size

6.8%

63.55%

24.13%

68.11%

Pricing

ShortPixel lets you optimize 100 images per month for free with no size restrictions. After that, you’ll need a paid plan starting at $4.99 per month for up to 5,000 images.

Real-World Testing Data Compared: Which Plugin Should You Choose?

Imagify

EWWW Image Optimizer

WP Smush

Compress JPEG & PNG images

ShortPixel

JPEG Lossless compression

4.39%

4.1%

4.9%

N/A

6.8%

JPEG Lossy compression

80.33%

N/A

N/A

39%

63.55%

PNG Lossless compression

32.01%

23.9%

11.2%

N/A

24.13%

PNG Lossy compression

81.31%

68.6%

N/A

75%

68.11%

It’s not a clear-cut decision for every single image type. But overall, I feel comfortable declaring Imagify to be the winner. It offered the highest compression levels for three out of the four tests.

While you might be able to achieve similar compression levels via the paid plans of other image optimization plugins, Imagify wins using freely available features.

In addition to its good compression levels, Imagify also has an excellent interface, which is another positive.

If you want a 100% free solution (and can’t fit within Imagify’s free plan), then WP Smush or EWWW Image Optimizer are good options.

I also like ShortPixel for its helpful add-on features.

Overall, though, Imagify wins when it comes to pure compression.

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