One of the key points to improve the loading speed and the Core Web Vitals of a WP site is the image optimization. Indeed, most of the data downloaded by the browsers of Internet users are actually images. It is therefore very important to optimize this type of file as much as possible. I have already explained in details the two main things to optimize the images of a WordPress site which are:

  1. Compress images to reduce their weight
  2. To have responsive images depending on the type of screen and its size

In this article, we will focus mainly on the 1st point (by the way, I recommend that you read this article first before continuing here) and on all the WordPress plugins that allow you to compress images… and thus reduce their weight. I had already presented you quickly 2 plugins for image optimization but today we will go much deeper and compare in details the best WP image compressor plugins. Let’s go!

Compressing your images: some important information

If you have already done some research on this matter, you may know that you can compress your images without loss of quality (“lossless”) or with loss of quality (“lossy”). If you only compress your images without loss of quality, the weight gain will be small and so will the performance improvement of your site. That’s why the standard in 2020 is to optimize your images with loss of quality (lossy) … Moreover if you test your site with a tool like GT Metrix or Google page speed, you will get warning messages if your images are not compressed with loss of quality.

So the idea is to find the right balance between the visual quality of your images and their weight (if you are a photographer, you may be more exigent about the quality). To compress your images, the WP image optimization plugins use different algorithms to optimize the quality of the images while reducing their weight as much as possible. In general, these plugins allow you to choose different levels of compression ranging from the best visual quality of the images (but with a heavier weight) to lower quality but much lighter images.

The idea of this article is therefore to compare the weight and visual quality of a few images after they have been compressed with different WordPress plugins (and different levels of compression). Of course, we will also compare the price of these plugins (because no, compressing your images properly is not free) as well as their different functionalities… The goal is obviously to find the best WordPress plugins for image optimization.

Comparison of the best image optimization plugins for WordPress

Let’s get down to business! Here are the different image optimization plugins that we will compare:

Note: It’s not easy to compare prices because some plugins charge per optimized image and others charge by weight of optimized images. Moreover, each time you upload an image to your media library, WP will create between 6 and 15 images of different sizes (maybe more) depending on your wp theme and plugins.

Plugins nbr of WP install Free trial Price
EWWW image optimizer 800’000 + 300 free credits by subscribing here (no credit card needed) 0.002$ / image
Shortpixel 200’000 + 100 free credits per months (no credit card needed) 0.001$ / image (cheaper the more images you buy)
Imagify 300’000 + 25 Mb of images per month (no credit card needed) 10$ for 1Gb of images (cheaper the mor Gb you buy)
Resmushit image optimizer 100’000 + free free
WP Smush 1 million + 7 days of free trial (credit card needed) 7$ per months without limitations
Tiny compress images 200’000 + 500 free credits per months (no credit card needed) 0.009$ per image after the first 500 (0.002$ per image after 10’000)
Kraken 40’000 + 100 Mb of free images (no credit card needed) 5$ per months for 500Mb (cheaper the mor Gb you buy)

All these plugins can be tried for free with a more or less generous quotas. The only plugin that will ask you for your credit card for a 7-day trial period is WP Smush (otherwise you won’t have access to lossy compression which is the only interesting type of compression).

Concerning the price, I have a strong preference for pricing by image rather than by weight. The idea of an image optimization plugin is to allow you to put your images in your media library directly after editing them (or from your camera) and without having to think about compression. For example, I often upload images that are between 5 and 10Mb and that come directly from my photo editing software. With a pricing by image size, I should first be careful not to export images that are too heavy to not blow my WP image optimization quota.

Comparison of the images visual quality and weight after compression with the different WP compressor plugins

As I said before, the idea is to have the best possible image quality/weight ratio after compression. So that we can make a visual comparison, I chose 3 different images (2 images in jpg format and one image in png format) that are 1600 pxs wide and that have already been optimized without loss of quality (this means that they no longer contain metadata but their pixels have not been modified).

Note: An important reminder depending on whether you are reading this article on mobile, tablet or desktop. Thanks to the srcset and sizes attributes, your browser will not display the same image depending on the type and size of your screen. So, if you read this article on a desktop, you will see either the 1600 pxs or 1024 pxs wide image depending on your browser. If you’re on a tablet or mobile device, you’re more likely to see either the 1024 pxs or 768 pxs wide image (maybe even the 300pxs wide). That’s why in the rest of the article, I will compare the optimizations for different image sizes.

Here are the 3 original images without loss of quality:

lossless image compression jpg 1
image 1 in jpg format with 435.3 kb for 1600pxs width
lossless image compression jpg 2
image 2 in jpg format with 744.5 kb for 1600pxs width
lossless image compression png
image in png format with 1.9Mb for 1600pxs width

So when I put these images in my media library without an optimization plugin, here are some of the different image sizes that are created with their weights. We will use these different sizes to compare the compression level of the plugins.

Image width of the image in pxs weight of the image in Kb
Image 1 jpg original 435.3 Kb
1536 pxs 117.3 Kb
1024 pxs 59.9 Kb
768 pxs 36.8 Kb
300 pxs 7.9 Kb
Image 2 jpg original 744.5 Kb
1536 pxs 212.7 Kb
1024 pxs 104.5 Kb
768 pxs 63 Kb
300 pxs 13.2 Kb
Image png original 1.9 Mb
1536 pxs 1.9 Mb
1024 pxs 929.1 Kb
768 pxs 535.1 Kb
300 pxs 87.4 Kb

Comparison of image 1 in JPG format with different plugins and compression types

For the 1st image, here are the results obtained after optimization with the different WordPress compressor plugins.

Plugin compression type image width in pxs image weight in Kb compression in %
EWWW (Pixel Perfect plus) original 429.8 1.26
1536 106.9 8.87
1024 55.2 7.85
768 33.8 8.15
300 7.5 5.06
EWWW (Premium) original 148.5 65.89
1536 90.6 22.76
1024 46.5 22.37
768 28.9 21.47
300 6.4 18.99
EWWW (Premium plus) original 150.1 65.52
1536 93.1 20.63
1024 52.9 11.69
768 30.4 17.39
300 7.5 5.063
Shortpixel (Glossy) original 158.2 63.66
1536 90.4 22.93
1024 59.9 0
768 33.8 8.15
300 7.9 0
Shortpixel (Lossy) original 54.6 87.46
1536 48.7 58.48
1024 33.6 43.90
768 21 42.93
300 4.9 37.97
Imagify (Aggressive) original 167.6 61.5
1536 63.6 45.78
1024 34.5 42.40
768 21.6 41.30
300 5.5 30.38
Imagify (Ultra) original 58.4 86.58
1536 35.2 69.99
1024 21.8 63.61
768 17.7 51.90
300 4.6 41.77
Resmushit (Regular = 92) original 251.8 42.15
1536 109.5 6.65
1024 56.3 6.01
768 34.8 5.43
300 7.5 5.06
Resmushit (80) original 121.1 72.18
1536 107.4 8.44
1024 55.2 7.85
768 34.1 7.34
300 7.3 7.59
Resmushit (70) original 90.8 79.14
1536 93.1 20.63
1024 47.5 20.70
768 29.6 19.57
300 6.4 18.99
WP Smush (Super smush) original 100.3 76.96
1536 95.2 18.84
1024 48.9 18.36
768 30.4 17.39
300 6.7 15.19
Tiny compress (default) original 150.1 65.52
1536 101.1 13.81
1024 58.2 2.84
768 32.3 12.23
300 8.7 -10.13
Kraken (Intelligent lossy) original 139.9 67.86
1536 105 10.49
1024 54.2 9.52
768 33.2 9.78
300 6.9 12.66

In order to be able to compare visually, here are all the images compressed in a gallery:

Comparison of image 2 in JPG format with different plugins and compression types

For the 2nd image, here are the results obtained after optimization with the different WordPress compressor plugins.

Plugin and compression type image width in pxs image weight in Kb compression in %
EWWW (Pixel Perfect plus) original 739.4 0.69
1536 200.8 5.6
1024 98.7 5.55
768 59.7 5.24
300 12.4 6.06
EWWW (Premium) original 305.2 59
1536 172.6 18.85
1024 84.9 18.76
768 51.2 18.73
300 10.7 18.94
EWWW (Premium plus) original 220.9 70.33
1536 143.8 32.4
1024 88.4 15.40
768 50.7 19.52
300 12.4 6.06
Shortpixel (Glossy) original 249.2 66.53
1536 172.1 19.09
1024 104.5 0
768 59.7 5.24
300 13.2 0
Shortpixel (Lossy) original 92.3 87.60
1536 73.1 65.63
1024 67.4 35.50
768 41.1 34.76
300 9.7 26.52
Imagify (Aggressive) original 391.7 47.39
1536 157.3 26.05
1024 78.4 24.98
768 47.6 24.44
300 10.7 18.94
Imagify (Ultra) original 323.4 56.56
1536 212.7 0
1024 61.6 41.05
768 63 0
300 9.2 30.30
Resmushit (Regular = 92) original 428.3 42.47
1536 202.5 4.8
1024 99.5 4.78
768 60.2 4.44
300 12.6 4.55
Resmushit (80) original 237.7 68.07
1536 198 6.91
1024 97.5 6.7
768 58.9 6.51
300 12.3 6.82
Resmushit (70) original 182.1 75.54
1536 171.4 19.41
1024 84.4 19.23
768 51 19.05
300 10.7 18.94
WP Smush (Super smush) original 206.7 72.24
1536 180.3 15.23
1024 88.7 15.12
768 53.6 14.92
300 11.2 15.15
Tiny compress (default) original 220.9 70.33
1536 149.6 29.67
1024 95.8 8.33
768 54.3 13.81
300 14.6 -10.61
Kraken (Intelligent lossy) original 490.5 34.12
1536 178.8 15.94
1024 89.9 13.97
768 56.1 10.95
300 11.9 9.85

And to compare visually, here again are all the compressed images in a gallery:

Comparison of image 3 in PNG format with different plugins and compression types

For the 3rd image, here are the results obtained after optimization with the different WordPress plugins. As it’s a PNG image, I also added in the 1st column if the plugin supports automatic conversion to JPG if the image doesn’t have transparency (in which case PNG is useless, which is the case for this image). For this image, the weight gain is huge if it is automatically converted to JPG:

Plugin and compression type image width in pxs image weight in Kb compression in %
EWWW (Pixel Perfect plus)
Auto conversion to JPG : YES
original 111.8 94.06
1536 99.4 94.85
1024 52.7 94.33
768 33.9 93.66
300 8.6 76.37
EWWW (Premium)
Auto conversion to JPG : YES
original 94.4 94.99
1536 84.5 95.62
1024 45.2 95.13
768 29.5 94.49
300 7.5 79.4
EWWW (Premium plus)
Auto conversion to JPG : YES
original 83.2 95.58
1536 74.6 96.13
1024 42.8 95.39
768 27 94.96
300 8.6 76.37
Shortpixel (Glossy)
Auto conversion to JPG : YES
original 121.9 93.53
1536 85.6 95.56
1024 55.8 93.99
768 33.7 93.70
300 5.8 84.07
Shortpixel (Lossy)
Auto conversion to JPG : YES
original 45.5 97.58
1536 38.8 97.99
1024 28.7 96.91
768 21.4 96
300 5.8 84.071
Imagify (Aggressive)
Auto conversion to JPG : NO
original 723.3 61.59
1536 1930 0
1024 929 0
768 535 0
300 36.4 0
Imagify (Ultra)
Auto conversion to JPG : NO
original 426.4 77.36
1536 1930 0
1024 929 0
768 535 0
300 36.4 0
Resmushit (Regular = 92)
Auto conversion to JPG : NO
original 667.8 64.54
1536 594.6 69.19
1024 274.7 70.43
768 161.2 69.87
300 29.3 19.51
Resmushit (80)
Auto conversion to JPG : NO
original 667.8 64.54
1536 594.6 69.19
1024 274.7 70.43
768 161.2 69.87
300 29.3 19.51
Resmushit (70)
Auto conversion to JPG : NO
original 667.8 64.54
1536 594.6 69.19
1024 274.7 70.43
768 161.2 69.87
300 29.3 19.51
WP Smush (Super smush)
Auto conversion to JPG : NO
original 591.6 68.58
1536 526.5 72.72
1024 247.5 73.36
768 145.6 72.79
300 27.5 24.45
Tiny compress (default)
Auto conversion to JPG : NO
original 533.8 71.65
1536 468.8 75.71
1024 217 76.64
768 128.8 75.93
300 24.9 31.59
Kraken (Intelligent lossy)
Auto conversion to JPG : NO
original 536.7 71.5
1536 473.7 75.46
1024 220.5 76.26
768 129.9 75.72
300 25.9 28.85

And to compare visually, here are all the images after optimization in a gallery:

Ranking of the WP plugins according to the weight and visual quality of the images after compression

Based only on the first 2 images (since not all plugins automatically convert png to jpg when necessary), here is a small ranking of the different plugins and compression types according to the % reduction (average size on images 1 and 2) and visual quality. Of course the visual quality ranking is subjective and is only my own opinion.

Plugins and compression type Compression ranking Visual quality ranking
EWWW (Pixel Perfect plus) 13 (5.4 %) 1
EWWW (Premium) 5 (28.6 %) 7
EWWW (Premium plus) 7 (26.4 %) 5
Shortpixel (Glossy) 11 (18.6 %) 3
Shortpixel (Lossy) 1 (52.1 %) 13
Imagify (Aggressive) 3 (36.3 %) 6
Imagify (Ultra) 2 (44.2 %) 12
Resmushit (Regular = 92) 11 (12.6 %) 2
Resmushit (80) 8 (19.8 %) 10
Resmushit (70) 4 (31.12%) 11
WP Smush (Super smush) 6 (27.9 %) 9
Tiny compress (default) 9 (19.6 %) 8
Kraken (Intelligent lossy) 10 (19.5 %) 4

Additional features of the WP image compression plugins

For the moment we have only compared the image compression efficiency of these different WP plugins (this is obviously the most important point). But some of these plugins have more features than others (we’ve already noticed this just with the conversion from png to jpg when necessary). Here’s a small list of additional features that might be useful depending on your needs:

  • Conversion to WEBP format: WEBP is a new image format for the web that is supposed to produce images at least 20% smaller for the same quality (compared to JPG and PNG). This format is supported by most modern browsers and could become the preferred format for images on the web. I haven’t switched to this format yet but when the time comes, I’ll be able to do it easily with one of these wp plugins.
  • Custom folders: In general, all your images are stored in the WordPress uploads folder. But sometimes, some plugins save them elsewhere. In these cases, it may be useful to be able to define some custom folders to optimize their images.
  • Responsive images and CDN: As I said at the beginning of the article, the second important point when talking about images for WordPress is to make sure that the right image is used according to the size and type of screen (the viewport). To do this, your theme must correctly implement the srcset and sizes attributes (more details in this article). But as many WP themes don’t do it properly, some of these plugins offer an interesting solution. Your images are optimized and served from different servers and especially delivered at the right size according to the viewport of the user who requests them. These solutions are generally more expensive and would need to be tested separately and compared to other more general CDN offers.
  • Exclude some image sizes: Some WP themes and plugins can create up to 15-20 different image sizes… Often, many of these image sizes are created for very specific things that you don’t necessarily use on your site (portfolio, woocommerce products etc…). It can therefore be very useful to disable the creation and/or optimization of certain image sizes to save space on your server and money (since optimizing images properly is not free).
Plugins WEBP conversion Custom folders Responsive images / CDN Image sizes
EWWW image optimizer YES YES YES YES (creation and/or optimization)
Shortpixel YES YES YES (by installing another plugin) YES (only optimization)
Imagify YES YES YES YES (only optimization)
Resmushit image optimizer NO NO NO NO
WP Smush YES YES YES NO
Tiny compress images NO NO NO YES (only optimization)
Kraken NO NO NO YES (only optimization)

Conclusions and best plugins for WordPress image optimization

To conclude, I would say that we must differentiate between two types of users:

  1. People who want to reduce the weight of the images as much as possible without worrying too much about the visual quality loss.
  2. People (like me) who want the best weight/image quality ratio

For people in the first category, I would say that nothing beats the Shorpixel plugin and its “lossy” compression. It’s the compression that creates the lightest images (but also those of lower quality in my opinion) and Shorpixel is also the cheapest plugin of all (and also one of the richest in terms of features). Both Imagify plugin‘s compressions are equally interesting, but their pricing by the weight of optimized images seems far less attractive to me than the price per image (unless you reduce your images before optimizing them, but that doesn’t make a lot of sense).

See the Shortpixel plugin

ewww image optimizerAs far as I’m concerned, I belong to the 2nd category of people and I’m looking to have the best weight/image quality ratio. So I directly eliminated the lossy compression of Shorpixel, Imagify ultra and resmushit 80 and 70 for their bad image quality (in my opinion). Next (compared to the % compression) come the Imagify aggressive compression and the Premium and Premium plus compression of EWWW image optimizer. Because from my point of view EWWW pricing is more attractive than Imagify’s and because EWWW is the plugin with the most features by far (not all of them have been listed above), it is the one I chose to use on all my sites. But if Shortpixel were to integrate an intermediate compression between its lossy and glossy algorithms, it might change my mind.

See the EWWW image optimizer plugin

Even if optimizing your WP images is not very expensive (we pay around 2$/month with EWWW for our 2 sites), if you don’t havethe budget for that, then the best free solution is still to use the Resmushit plugin with an image quality between 70 and 80 I would say.

That’s it for this detailed comparison of the best WP image compressor plugins. While doing my own researches, I haven’t found any information on the web comparing precisely these different tools. So I hope my article will be useful and don’t hesitate to ask me your questions in the commentsection below (and to share the article if you found it useful 😉 )

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Note: This article contains affiliate links for the image optimization plugins I recommend. If you subscribe to one of these plugins, we will get a small commission and you won’t pay a penny more. This way, you will support us in the creation of such free and independent articles.

Benoit Luisier

Self taught web developer and a travel addict , I share on Novo-Media my tips about the more "techy" part of topics like web development, Wordpress, Web optimisation or SEO. I'm also the creator of the google maps Wordpress plugin Novo-Map

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Comments

  1. Michael Web Taiwan says

    Hi Benoit
    Thank you for you detailed comparison!
    1) EWWW has a free version forever on WP directory, why you didn’t mention it? Not worth it?
    2) what about WP Compress and Gumlet image optimizer?
    3) If we compress images with tools online like tinyjpg.com or kraken.io then we don’t need to install these plugins?
    4) Your sentence “we pay around 2$/month with EWWW for our 2 sites” how can you do this? The EWWW for 2-10 sites is $15/month or $150/year, which option or did you take?

    • Benoit Luisier says

      Hi Michael,
      1) If you use the free version you don’t have access to the premium compressions which are the one you should use to get the best size/quality ratio
      2) Haven’t tested those… hard to try all the plugins out there 😉
      3) you still need to have those plugins because when you upload a compressed image in your media library, WP will generate several copies of this image in different sizes. All those copy won’t be optimized if you don’t use a plugin
      4) You don’t have to use the monthly subscription plan… you can also subscribe to the image compression plugin (without the image CDN and all the other stuff) only and only pay for what you compress.

  2. Yohance Salimu says

    thank you for this article. I rrrreally needed it.
    I belong in the first camp. Speed kills. peace.

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