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Compared: The 10 Best WordPress Image Optimization Plugins

Images usually account for the bulk of the page size so optimizing images by compressing them is a crucial step to make your website pages load faster.

There are multiple WordPress image optimization and compression plugins available for the job and it’s easy to feel confused while trying to pick the right image compression plugin for your website.

To make your search easier, I have compared the 10 most popular WordPress image optimization plugins available right now.

There are 4 tasks expected of a robust image optimization plugin: compression, lazyload, specifying image dimensions, and WebP conversion.

Image compression is self-explanatory and the most obvious function but the other 3 are no less important. Lazyload ensures that the image is visible only when it’s in the viewport of the user to conserve bandwidth and speed up the page load.

By specifying the image dimensions beforehand, the browser reserves the exact space required to display the image. This helps to minimize the Cumulative Layout Shift (CLS), a Core Web Vital metric.

Finally, converting images to the WebP format further reduces the image size and serves them in the most compatible format for modern browsers like Google Chrome.

Hence a plugin has to be seen in its totality and not just in terms of its raw image compression capabilities.

best image optimization plugin

In this article, I will compare not just the features of the 10 most popular image optimization plugins but, more importantly, I will test their image compression abilities.

Setting up the test

For this comparison, I used the following PNG image having a size of 301 KB.

best image compression plugin test

Next, I excluded the image EXIF data in all the plugins for better results. Some plugins offer lossy as well as lossless compression, so I tested both settings.

While some others only provide one type of compression.

Now, let’s get started.

1. Smush

Smush by WPMU Dev is the most popular WordPress image optimization plugin which is active on more than one million websites. It offers lossless compression, lazyload, image resizing, and bulk compression in the free version.

You can compress images up to 5 MB in size for free. Beyond this limit, you will need the Pro version. Also, WebP conversion, lossy compression, and cloud compression are available only in the paid version of Smush.

Earlier, Smush did not compress the featured image size in the free version but now this limit has been removed and you can compress all image sizes.

Here are the test results:

Original ImageCompressed Image (lossless)
301 KB301 KB (o%)

I was quite surprised that Smush did not compress the image at all. Rather it displayed an “already optimized” message when I tried to manually compress the image. The fact that it is the most popular image optimization plugin makes it even more disappointing.

I am sure that the plugin would achieve good results in lossy mode but as I mentioned earlier, it’s a pro-only feature.

👉🏾 Check out Smush

2. ShortPixel Image Optimizer

ShortPixel is another popular image compression and optimization plugin. The free version allows you to compress 100 images each month. If you need to compress more images, you will need to upgrade to a paid plan.

It has minimal impact on your resources since the image optimization is handled by ShortPixel’s cloud servers.

There is no limit on the image size in the free plan. The downside is that each image size counts as one image credit. So typically a single image will consume about 5 credits since WordPress generates 3 thumbnails by default for every image. Your theme may generate one or two additional image sizes.

Don’t Miss: The 7 best WordPress optimization plugins

So effectively, you won’t be able to compress more than 20 images each month on the free plan. Further, it has a built-in WebP conversion feature but each image conversion consumes 1 credit. So if you activate this option, your free quota will be over before long.

ShortPixel offers 3 levels of compression – lossy, lossless, and glossy. You already know what the first two mean. The glossy compression setting is a very useful feature for photographers who want to compress high-resolution images without sacrificing image quality.

I also liked the PDF compression feature in ShortPixel and it will be useful if you offer PDF downloads or embed PDFs on your site.

Another cool feature is the PNG to JPEG conversion that results in much higher savings since JPEG files are typically much smaller in size compared to their PNG counterparts.

Now, let’s check out the test results.

Original ImageLossless CompressionLossy Compression
301 KB297 KB (4.7%)106 KB (65%)

You can see that the lossless compression is nothing special but ShortPixel achieved a 65% reduction in image size using lossy compression. Also, there was no noticeable quality loss. This implies that if you’re willing to pay for the premium version, you can achieve good results with this plugin.

👉🏾 Check out ShortPixel

3. EWWW Image Optimizer

EWWW Image Optimizer is the most popular free image optimization plugin with close to one million active installs.

There are no limits on the number or size of the image that you can compress for free.

The plugin compresses the images on your server, unlike on a cloud server. If you upgrade to their premium plan, you get access to their cloud-based optimization service as well as access to the API service.

The settings are pretty straightforward to understand. EWWW offers lazyload, image scaling, add missing image dimensions, and WebP conversion for free.

The plugin also offers PNG to JPG conversion, JPG to PNG conversion, as well as GIF to PNG conversion. So as far as features are concerned, EWWW is one of the best image optimization plugins to use on your WordPress website.

But what about its compression abilities? Check out the results below.

Original ImageLossless CompressionLossy Compression
301 KB297 KB (1.35%)108 KB (64%)

You can see that just like ShortPixel, EWWW really shines with lossy compression. The lossless compression achieved was pretty insignificant.

We have been using the EWWW image optimization plugin on PassionWP for a very long time and can vouch for its image optimization abilities.

👉🏾 Check out EWWW Image Optimizer

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4. reSmush.it

reSmush is an image optimization API service that offers a WordPress plugin to compress your images in bulk or individually. The service is free for images up to 5 MB in size.

You can compress PNG, JPG, and GIF images using the reSmush plugin without any limits on the number of images. Also, you can exclude individual images from the bulk optimization process.

One of the unique features is that you can set the image quality that the plugin will output on a scale from 1 to 100. If you set the image quality to 100, the plugin will perform lossless compression. Anything lower than 100 will result in lossy compression.

I tested the lossless compression (100% image quality) and lossy compression (90% image quality) of the plugin and here are the results:

Original ImageLossless CompressionLossy Compression
301 KB110 KB (64%)110 KB (64%)

As you can see both the settings resulted in the same level of image compression. Also, I did not notice any quality loss in the lossy compression mode.

So, if you can do without some other features like WebP conversion (which is coming soon according to the developers), image scaling, and lazyload, this is one of the best free image optimizer plugins available today.

👉🏾 Check out reSmush.it

5. Optimole

Optimole is an advanced cloud-based image hosting and optimization service.

The images are not only optimized externally on the Optimole servers but they are also hosted and served from their cloud servers thus saving precious bandwidth on your site.

There is no limit on the size or the number of images you can optimize with Optimole. Rather the free plan is limited to 5000 monthly visits. Beyond this, you will need to upgrade to their paid plans.

So, if you’re running a low-traffic site, you will probably not need to upgrade but once your site traffic picks up, the free quota will be gone in no time.

You can pick amongst three different image quality settings: Low, Medium, and High.

The Optimole plugin is jam-packed with features, the important ones are listed below:

  • Image replacement: replaces the images with the ones optimized on the Optimole cloud platform
  • Image scaling and lazyload
  • Automatically downgrade the image quality on slower networks
  • GIF to video conversion
  • Smart cropping by detecting the center of the images and focusing on it
  • Exclude lazyload for the initial images in above the fold content

I tested Optimole’s image compression feature on the Medium and High image quality settings.

Original ImageHigh QualityMedium Quality
301 KB121 KB (59%)121 KB (59%)

Surprisingly, the results on both the quality settings were the same. The good thing is that there was no visible quality loss on either setting.

👉🏾 Check out Optimole

6. Imagify

Imagify is another popular image optimization plugin for WordPress developed by WP Media, the creators of the popular WP Rocket cache plugin.

It offers the usual bells and whistles expected of a quality image optimization plugin like compression, WebP conversion, and image scaling. However, it is surprising that Imagify does not offer an image lazyload feature.

The good news is that if you’re already using WP Rocket, then you don’t need to worry about lazyload since it’s a built-in feature of WP Rocket.

Like Optimole and ShortPixel, Imagify optimizes your images on its cloud servers using its API. The free plan offers 25 MB of image optimization quota. Beyond this, you will need to upgrade to their premium plans.

However, most users will never need to upgrade since 25 MB is a quite generous monthly offering.

Imagify offers three compression settings: Normal (lossless), Aggressive (lossy), and Ultra (lossy).

I recommend you test out each setting to see which one strikes the right balance between good image quality and lower size.

I tested the image compression on all three modes:

Original SizeNormal (lossless)Aggressive (lossy)Ultra (lossy)
301 KB298 KB (4.5%)123 KB (59%)118 KB (61%)

The Aggressive mode returned a good compression of 59% but the Ultra mode expectedly achieved better compression. I would recommend you test different image sizes on your site before picking between the Aggressive and Ultra modes. If in doubt, go with Aggressive.

👉🏾Check out Imagify

7. TinyPNG

As its name suggests TinyPNG is an image compression plugin but it does not do anything other than compressing PNG, JPEG, and WebP images. It uses its cloud servers for image compression via API.

You can compress 500 images on the free plan per month. One thumbnail counts as one image.

The good part is that you can exclude the sizes you wish to exclude from the image compression process.

There is no option to choose between lossy and lossless compression. The plugin outputs lossy images by default and here are the test results.

Original SizeLossy Compression
301 KB87 KB (71%)

As you can see, TinyPNG achieved an impressive level of compression with no visible image quality loss. Till now, it’s the highest compression we have seen in this comparison.

👉🏾 Check out TinyPNG

8. Robin Image Optimizer

Robin Image Optimizer is a free-to-use plugin with no limits on the number of images optimized except a 5 MB image size limit.

It makes use of the reSmush.it API to optimize the images and since the API is free, the Robin plugin is also free to use.

There are three compression levels to choose from Lossless, Lossy, and High. You can also set a custom image quality setting, which I found very useful. Also, you can select which image sizes you would like to optimize.

The unique feature of Robin is that it offers a Cron managed image optimization schedule in which the images are optimized at the defined interval of, say, every 5 minutes.

Robin Optimizer lacks lazyload or image scaling options. Also, WebP conversion is a Pro feature.

Now, let me present the test results for this plugin.

Original SizeLossless CompressionLossy Compression
301 KB110 KB (63%)110 KB (63%)

You can see that the same result was achieved on both the settings and the fact that you can compress unlimited images using an API makes Robin Optimizer a wonderful free solution for WordPress users.

👉🏾 Check out Robin Image Optimizer

9. WebP Converter

WebP Converter works on a simple principle that WebP images are substantially smaller in size compared to other formats. Based on this, it converts all the PNG, JPG, JPEG, and GIF images on your site to WebP format using lossy compression.

Apart from this, it offers no other features. So without further ado, here are the results.

Original SizeLossy Compression
301 KB87 KB (71%)

The compression ability of WebP Converter is pretty good with 71% compression achieved on the test image. Also, the plugin is completely free to use so it’s an option to seriously consider for your website.

👉🏾 Check out WebP Converter

10. Optimus

Optimus is an image optimization plugin developed by KeyCDN. It offers cloud-based image compression and conversion to WebP format.

But the biggest downside is that the free version allows compression of images not more than 100 KB in size which is such a pity as the images that we actually need to compress will almost always be more than 100 KB in size.

Due to the size limitation, I could not test drive the Optimus plugin.

👉🏾 Check out Optimus

Which Image Optimization plugin is the best?

If you have reached this far, it means you’re really interested in knowing which of the above 10 plugins you should pick for your website. That’s great because I am as pumped up as you are.

So let’s get straight to the point.

Best free image optimization plugin

After considering the image compression capabilities, and other features, I have to admit that EWWW Image Optimizer is the best free image optimization plugin for WordPress. It does not have any restriction on the size or number of images optimized per month.

Additionally, it offers lazyload, image scaling, WebP conversion, and adding missing dimensions as well. All this for free. The lossy compression achieved with EWWW was also quite impressive.

WebP Converter came second because of the higher level of compression achieved but it lost out on other features. reSmush and Robin Image Optimizer were jointly tied for the third position. Both of them achieved the same level of compression since they use the same API.

🥇 EWWW Image Optimizer

🥈 WebP Converter

🥉 reSmush.it and Robin Image Optimizer

Best premium image optimizer plugin

The competition among the premium, or more correctly freemium, plugins was stiff. The lossy compression achieved by every plugin was almost equal. All the premium plugins compress images on the cloud so this feature did not matter.

Although TinyPNG achieved the highest compression, it does not offer any other feature.

I will pick Imagify as the best premium image optimization plugin since it strikes the right balance between its free and premium plans. The 25 MB monthly optimization quota will be sufficient for most users. In addition, it’s premium plans are quite affordable too starting at $4 per month.

Optimole scored second place owing to its cloud hosting and other cool features. ShortPixel came in a close third because of the impressive compression levels achieved and useful features like PNG to JPEG conversion.

🥇 Imagify

🥈 Optimole

🥉 ShortPixel

Which one did you choose?

Over to you now. I hope you enjoyed reading this comparison as much as I enjoyed writing it. I would love to know which image optimization plugin you’re using and why in the comments below.

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About Trishan Mehta

Trishan Mehta is a WordPress fanatic since 2009. When not WordPressing, he is busy exploring hidden natural getaways whenever he can grab an opportunity. You can grab his WordPress SEO eBook to get up to speed with WordPress SEO.

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