How image compression works
Image compression removes redundant or less noticeable data from a file so it takes up less space. Lossy formats such as JPEG and WebP can reduce file size dramatically by simplifying fine details that are difficult for the human eye to notice. The result is a smaller file that still looks close to the original at an appropriate viewing size.
For web publishing, compressed images are not just a nice extra. They directly affect page speed, mobile data usage, and search engine performance. A large hero photo can add hundreds of kilobytes to a page, while a properly optimized version can deliver the same visual impact at a fraction of the size.
Recommended settings by use case
| Use case | Recommended format | Quality | Maximum width |
|---|---|---|---|
| Website hero image | WebP | 75-85% | 1920 px |
| Blog content image | WebP or JPG | 70-80% | 1200 px |
| Email newsletter | JPG | 75-85% | 800 px |
| E-commerce product photo | WebP | 80-90% | 1600 px |
| Social media post | JPG | 80-90% | 1600 px |
Why compressed images improve Core Web Vitals
Largest Contentful Paint (LCP) measures how quickly the main content of a page becomes visible. Large images are one of the most common causes of a slow LCP score. When you compress images before upload, the browser downloads less data and can paint the hero image sooner. That improvement matters on mobile connections and in regions where broadband is less consistent.
Lossy vs. lossless compression
Lossless compression keeps every pixel of the original image but can only remove repetitive data. Lossy compression removes some detail and can achieve much smaller files. Most web photos should use high-quality lossy compression. PNG is a better choice for screenshots, logos, and graphics with sharp edges or transparency, but it should be used carefully because photographs saved as PNG are usually much larger.
Frequently asked questions
Can I compress multiple images at the same time?
Yes. Select several files in the file picker or drag multiple files into the drop zone. The same quality, format, and width settings are applied to every file.
What is the best quality setting for web images?
For most photographic content, 75-85% produces a strong balance between file size and visual quality. Start at 80% and adjust based on the image content.
Why is my PNG image still large after compression?
PNG is designed for lossless graphics and is not efficient for photos. Converting a photographic PNG to WebP or JPG usually produces a much smaller file while preserving acceptable quality.
Related tools
After compressing, you may also need to convert the format, resize the image, or crop it for a specific layout.