Image Optimization Guide
Learn proven techniques to optimize images for the web. Use our free Image Optimizer to compress and resize images directly in your browser.
Compression Techniques
Image compression falls into two categories. Lossless compression reduces file size without any quality loss by removing redundant metadata and optimizing pixel data. Lossy compression achieves much smaller file sizes by discarding some visual information that is less noticeable to the human eye. A quality setting of 80-85% for JPEG and 75-80% for WebP typically offers the best balance.
Quality Settings Guide
| Quality | JPEG | WebP | Use Case |
|---|---|---|---|
| 90-100% | Excellent | Excellent | Photography portfolios, print-quality |
| 80-89% | Great | Great | General web use, blog images |
| 60-79% | Good | Good | Thumbnails, background images |
| 40-59% | Fair | Fair | Preview images, placeholders |
| Below 40% | Poor | Poor | Avoid — visible artifacts |
Responsive Images and Lazy Loading
Serving appropriately sized images for each device is critical. Use the srcset attribute to define multiple image resolutions and let the browser choose the best one. Combine this with loading="lazy" to defer offscreen images, reducing initial page weight and improving Largest Contentful Paint (LCP).
Web Performance Impact
Largest Contentful Paint (LCP)
Optimized images load faster, improving LCP by 20-40%
Total Page Weight
Compression reduces image weight by 50-80%
Bandwidth Savings
Responsive images save 30-50% on mobile data transfer
Time to Interactive
Smaller images reduce CPU time for decoding