The plugin matters less than most comparisons suggest. What you upload, and how many image sizes your theme registers, decide more than any setting inside one.
This site is a browser-based compressor, which overlaps with what these plugins do at upload time. We have deliberately not written a ranked list of named plugins: we compete with some of them, several are commercial products whose terms change, and a leaderboard would be out of date within a year.
The criteria below are the ones that actually differentiate them, and they are stable.
Three changes cost nothing and usually outperform installing anything.
Compress before uploading. WordPress generates a copy at every registered size from whatever you give it, so one oversized original becomes a dozen oversized derivatives. Around 2000 pixels on the longest edge at quality 80 is right for almost every theme.
Audit your registered image sizes. A default install creates a few; a theme with a page builder can register a dozen, each generated for every upload. Most are never used. Removing them shrinks your uploads directory and speeds up every future upload.
Check what is actually served. Open a page in the browser's network panel and sort by size. It is common to find a CSS background image or a slider bypassing WordPress's responsive sizing entirely — no plugin will fix that.
Do these and a plugin has an easy job. Skip them and it has an impossible one.
<picture> element — each interacts differently with page caching, and a mismatch causes the wrong format to be served from cache.In practice the largest improvements on most WordPress sites are not from compression settings at all.
Everything below runs in your browser, so you can test any of this on your own files without uploading them.
One setting across a whole folder, processed in parallel, downloaded as a ZIP.
Open the toolTypically 25–35% smaller at matched quality. The standard web win.
Open the toolBy pixels or percentage, aspect ratio locked, across a whole batch.
Open the toolFull resolution kept, quality still invisible to the eye.
Open the toolQuestions
Every answer below is present in the page source, expanded, so it can be read without opening anything.
Only for jobs you cannot do at upload time — bulk converting an existing library to WebP, and serving the right format per browser. If you compress and resize before uploading, a plugin adds considerably less than its marketing implies.
We deliberately do not rank them: we overlap with what they do, several are commercial products whose terms change, and any list would be stale within a year. The criteria on this page are what differentiate them, and they do not go out of date.
It is a genuine trade-off. You get better encoders and no load on your own hosting; you also create a data-processing relationship and a dependency on their uptime and pricing. For a site handling anything sensitive, prefer local processing.
Check before you install, not after. Some leave the converted files and fall back cleanly; others break image delivery until you undo their changes. It is the question people most often wish they had asked.
Partly. It can reduce bytes, which helps LCP. It can also hurt if it lazy-loads your hero image — that delays the very element the metric measures, and blanket lazy-loading settings do it routinely.
Yes, clearly. WordPress generates every registered size from your upload, so an oversized original multiplies into a dozen oversized derivatives. Compressing afterwards means a second lossy pass over files that were made badly.
From the blog
Longer, more practical guides from the blog.
Resize before you compress. Measured on one photograph: half the width at quality 80 produced a 16.4 KB file, while full width at quality 40 produced 20.6 KB and looked far worse. The order of operations matters more than the settings.
8 min read
WebP produced a 27.0 KB file against MozJPEG's 41.1 KB on the same photograph at slightly higher measured fidelity — 34% smaller. It also produced a larger file than JPEG on random noise. The advantage is real and content-dependent.
9 min read
Quality 80 is not 80% of anything. It is an index into a quantisation table. Measured on one photograph: dropping from 100 to 90 removes 77% of the file and 4.2 dB of fidelity; dropping from 40 to 30 removes 17% and costs almost as much.
8 min read