Images are often the heaviest part of a web page; across HTTP Archive's year-by-year statistics, images regularly make up a large share of the bytes a page transfers. Optimizing images not only speeds up loading and improves user experience — it also helps search engines index your pages and improves the LCP (Largest Contentful Paint) metric in Core Web Vitals. This article compares three formats, JPEG, PNG and WebP, and gives you a compression workflow you can apply right away.
When to Use Each Format
| Format | Characteristics | Recommended use |
|---|---|---|
| JPEG | Lossy compression, small file size, extremely wide compatibility | Photos, complex gradients, real-world scenes |
| PNG | Lossless compression, supports alpha transparency | Icons, logos, screenshots, transparent assets |
| WebP | Lossy or lossless, usually 25%–35% smaller than JPEG | Web use on modern browsers — the go-to format |
How to Choose Compression Quality
- Page hero images (60%–80%): A balance between quality and file size that suits most pages.
- Thumbnails and list images (40%–60%): You can drop the quality a little to get much smaller files.
- High-resolution printing (90% or above): Keep the quality high, or switch to PNG.
- Transparent assets: Prefer PNG; WebP also supports transparency, but watch out for compatibility.
A 5-Step Online Compression Workflow
- Upload your images: Open the image compressor, then click or drag in your images — you can process several at once.
- Choose the output format: For web use, pick WebP to balance file size and quality.
- Adjust the compression quality: Start at 80% and lower it step by step while previewing, watching for any visible difference.
- Limit the maximum dimensions: If the original is very large, set a maximum width (e.g. 1920px) to cut the file size dramatically.
- Export and compare: Download the compressed result and compare file size and quality against the original.
Tip: all image processing happens locally in your browser — files are never uploaded to a server, so it's safe to compress images that contain sensitive information.
Frequently Asked Questions
Does compressing an image hurt its quality?
Lossy compression (JPEG/WebP) does lose some quality, but with sensible quality settings the difference is nearly invisible to the eye while the file size drops dramatically.
Is WebP supported by all browsers?
WebP is natively supported by all major browsers, including Chrome, Firefox, Edge and Safari. If you need maximum compatibility, you can fall back to JPEG.
How efficient is batch compression?
Online tools let you drag in multiple images at once, compress them in a batch and export them all — ideal when you're processing a large set of assets.
References
- WebP image format — Google Developers: https://developers.google.com/speed/webp
- Canvas API image processing — MDN Web Docs: https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API