What Does "Reducing Image Size" Actually Mean?
When people talk about reducing image size in WordPress, they usually mean reducing the file size in kilobytes or megabytes — not the pixel dimensions. Both matter, and the best approach combines them. There are four levers you can pull:
- Quality reduction — serve images at 75–80 quality instead of 95+
- Format conversion — use WebP or AVIF instead of JPEG or PNG
- Dimension capping — prevent oversized originals from being stored
- Lazy loading — defer images below the fold so they are not downloaded until needed
Quality Reduction
The quality slider in Divi Image Compressor lets you choose a value from 1 to 100. The default is 80. Images at quality 80 are indistinguishable from those at quality 95 when viewed at normal screen resolution — but the file size difference is significant. A typical JPEG at quality 95 might be 800 KB; the same image at quality 80 is typically 200–350 KB.
WebP Conversion
WebP uses more advanced compression than JPEG, producing images typically 25–35% smaller at the same visual quality. All modern browsers support WebP, and WordPress has supported it natively since version 5.8. Set the Output Format to "Convert to WebP" and run Bulk Compress to update your existing library.
AVIF — Even Smaller Files
AVIF is an even newer format achieving 40–50% smaller file sizes than JPEG. It is supported by Chrome, Firefox, Edge, and Safari (since version 16.4). Your server needs PHP 8.1+ or ImageMagick with AVIF support — the settings page shows whether your server is compatible.
Maximum Dimension Limits
Setting a maximum width and height caps the pixel dimensions of every uploaded image. Combined with compression and format conversion, this can reduce file sizes by 90% or more.
Lazy Loading
The Lazy Load feature defers loading of images below the visible page. The native loading="lazy" attribute tells the browser not to download an image until it is about to enter the viewport. This reduces initial page load data significantly without making images any smaller on disk.
Compression Statistics
After the plugin is running, the Compression Statistics dashboard shows your lifetime savings. Typical sites with unoptimised images see a 60–80% reduction in total image library size after a full bulk compression run.
Frequently Asked Questions
What is the recommended quality setting for WordPress images?
Quality 80 is the recommended starting point for most sites. WordPress' own default is 82. Divi Image Compressor's default is also 80. For photography portfolios or print-focused sites, quality 85–90 is more appropriate.
Should I use WebP or AVIF for my WordPress site?
WebP is the safer choice for maximum browser compatibility. AVIF offers better compression but has slightly lower support (not all server configurations support AVIF encoding). If your server supports AVIF and your audience uses modern browsers, AVIF will give you smaller files.
Does compressing images affect my site's SEO?
Directly, no — Google cannot see image quality. Indirectly, yes — smaller images load faster, which improves Largest Contentful Paint (LCP), one of Google's Core Web Vitals ranking signals. Faster LCP positively affects your search rankings.
Can I compress images without installing any plugin?
You can compress images manually in Photoshop, GIMP, or online tools like Squoosh before uploading. But this does not help existing library images, does not apply automatically to new uploads, and cannot batch-process a library of hundreds of images. A plugin is far more practical for ongoing site management.
Will reducing image quality make my website look worse?
Not at quality 80. The difference between quality 80 and quality 95 is imperceptible at typical screen resolutions (72–144 PPI). The artifacts of over-compression only become visible at quality settings below about 60, and only on close inspection.