WordPress Image Compression Plugins Compared: ShortPixel, Imagify, EWWW and Smush
Compare WordPress image compression: built-in features, ShortPixel, Imagify, EWWW Image Optimizer, Smush, CDN optimisation, WebP, AVIF and what to check.
On this page
- WordPress creates image sizes and applies light compression, but does not bulk-optimise or convert old images.
- ShortPixel, Imagify, EWWW and Smush differ mainly in where processing happens, credit limits and format delivery.
- Use a single optimisation tool, test WebP or AVIF delivery, and let an existing image CDN do the job if you have one.
Every WordPress site needs some form of image compression, but there are several ways to get it: WordPress's own features, a compression plugin, your caching plugin or host, or a CDN that optimises images as it delivers them. They overlap a lot, and running two at once can cause more trouble than it saves. This guide compares the main approaches so you can choose one sensibly. For the basics of resizing, alt text and lazy loading, start with image optimisation for WordPress.
What WordPress already does
- Multiple sizes: each upload is saved in several sizes (thumbnail, medium, large and any your theme adds), and browsers pick a suitable one through responsive image markup
- Big image scaling: very large uploads are scaled down to a sensible maximum, with the original kept on the server
- Some compression: the resized copies are saved with moderate compression
- Modern formats: recent versions accept WebP uploads, and AVIF where the server supports it
- Lazy loading for images further down the page
What WordPress doesn't do on its own is compress aggressively, convert your existing JPEGs and PNGs to WebP or AVIF, or bulk-optimise an old media library. The WordPress performance team's free Modern Image Formats plugin can create WebP or AVIF versions of new uploads, and the plugins below cover the rest.
Lossy, lossless and modern formats in plain English
- Lossless removes hidden data without changing how the image looks. Savings are modest.
- Lossy discards detail most people won't notice. Savings are much larger, and for photos it's usually the right choice.
- WebP is supported by all modern browsers and is usually much smaller than JPEG or PNG at similar quality.
- AVIF can be smaller still, though it takes more processing to create, so check how your tool and host handle it.
Some tools offer a middle setting between lossy and lossless. Whatever you choose, check a few product photos, faces and images containing text at full size before bulk-processing the whole library.
The main plugins compared
These are some of the best-known compression plugins. Features, free limits and pricing change often, so check each one's current plans before you decide.
| Plugin | Where compression happens | Generally known for | Worth knowing |
|---|---|---|---|
| ShortPixel | ShortPixel's cloud servers | Lossy, glossy and lossless modes, WebP and AVIF creation, bulk optimisation | Credit-based plans with a small free monthly allowance; generated thumbnails usually use credits too |
| Imagify | Imagify's cloud servers | Simple settings, WebP and AVIF conversion, bulk optimisation | From the team behind WP Rocket; the free plan has a monthly limit |
| EWWW Image Optimizer | Your own server in the free version, with paid cloud options | Free local compression without monthly quotas, WebP conversion, and an image CDN in paid plans | Local compression needs your host to allow the tools it uses, and it uses your server's resources |
| Smush | WPMU DEV's servers | An easy free version with basic compression and lazy loading | Stronger compression, next-gen formats and a CDN have mainly been paid features; check what the free version currently includes |
Other reputable tools exist. The bigger decisions are where processing happens, how new formats are delivered and what happens if you stop paying.
CDN and host-level optimisation
- Image CDNs resize, compress and convert images on the fly, serving each visitor a suitable size and format. Options include Jetpack's site accelerator, image features on some Cloudflare plans and dedicated image CDN services. See what a CDN is for how this works.
- Caching plugins and hosts: LiteSpeed Cache, for example, offers image optimisation through its QUIC.cloud service, and some hosts include image tools in their plans.
The upside is no processing load on your server and no pile of extra files. The downsides: you depend on the service staying active, image URLs may point to another domain, and some setups need careful testing with your cache and page builder. If a CDN already optimises your images, you probably don't need a compression plugin doing the same job.
How WebP and AVIF actually get served
Creating WebP files is only half the job; the site also has to deliver them. Tools use one of these methods:
- Server rewrite rules: the server serves the WebP version to browsers that support it. This works well on Apache and LiteSpeed; Nginx needs extra configuration.
- Picture tags: the plugin rewrites your HTML so each browser chooses the best format. Reliable, but it can occasionally upset theme or page builder styling.
- CDN delivery: the CDN picks the format for each visitor.
- Replacing originals: uploads are converted and served as WebP directly. Simple, but keep backups of the originals.
Afterwards, check it's working. Inspect a few images in your browser's developer tools or run a speed test and confirm WebP or AVIF files are being served. CSS background images and slider images are often missed. The guide to speed test tools explains which reports to look at.
What to look for before you choose
- Bulk optimisation for your existing library, not just new uploads
- Backups of originals, so you can restore or re-compress later; they do use disk space
- Control over compression level, ideally with a before-and-after preview
- WebP and AVIF support, with a delivery method that suits your server
- How thumbnails are counted on credit-based plans, since one upload can produce many sizes
- What happens if you cancel: compressed files usually stay, but CDN-based optimisation stops
- Server load if processing happens on shared hosting
- Compatibility with your theme, page builder, caching plugin and WooCommerce galleries
Most important of all, use one image optimisation tool. Two plugins compressing the same files, or a plugin and a CDN both converting formats, means wasted credits, odd results and bugs that are hard to trace.
Which approach suits your site?
| Type of site | A sensible approach |
|---|---|
| Small brochure site with few images | Resize before uploading, then use a free plugin tier or your caching plugin's image feature |
| Blog or portfolio with a large library | A plugin with bulk optimisation and WebP, run once over the library and then on new uploads |
| WooCommerce store | A plugin or image CDN with WebP or AVIF, tested on product galleries and category pages; see WooCommerce speed optimisation |
| Busy or international site already on a CDN | Let the CDN handle formats and resizing, and skip a separate compression plugin |
No plugin fixes images uploaded far larger than needed, or a hero image that's lazy-loaded; those still need fixing at the source.
Not sure which setup your site needs? Image optimisation is usually one of the first steps in my WordPress speed optimisation work. Running an online store? See WooCommerce development.
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