Images make up the majority of downloaded bytes on web pages and media feeds. Choosing the optimal format directly affects website speed, storage footprints, and user experience.
Format Overview: JPEG vs WebP
JPEG (created in 1992) has been the standard photography format for decades. It uses discrete cosine transform (DCT) lossy compression to reduce image file size by discarding high-frequency visual details.
WebP (introduced by Google in 2010) is built on the VP8 video codec predictive coding engine. It calculates block predictions from neighboring pixels, allowing it to preserve sharp edges and subtle color gradients at much lower bitrates.
Compression Efficiency & Visual Quality
In standard benchmarks:
- Lossy WebP files are on average 25%–34% smaller than comparable JPEG images at identical SSIM (Structural Similarity Index) ratings.
- WebP avoids blocky 8x8 DCT compression artifacts common in low-bitrate JPEGs, replacing them with smoother, less distracting gradients.
Feature Comparison: Transparency & Lossless
A significant advantage of WebP is its versatility. While JPEG is strictly lossy and has zero support for transparency, WebP supports:
- Lossless Compression: 26% smaller file sizes compared to PNG.
- Alpha Channel Transparency: True 8-bit transparency with lossy or lossless compression.
- Animation: Full replacement for heavy animated GIF files.
Browser & Ecosystem Compatibility
Today, WebP is supported by over 97% of global web browsers, including Chrome, Safari, Firefox, Edge, and iOS/Android mobile runtimes. All modern CMS platforms and web frameworks support WebP out of the box.
WebP vs PNG: Transparency, Size and Quality
PNG is lossless: every pixel is stored exactly, which is why it became the default for logos, screenshots, interface graphics and anything with a transparent background. WebP can do the same job. In lossless mode it also keeps every pixel and the full alpha channel, and Google measured those files at about 26% smaller than the equivalent PNG. When a transparent graphic does not need to be pixel-perfect, lossy WebP with transparency typically lands at around a third of the PNG size.
PNG still wins in three places: master files you will keep editing, images that need more than 8 bits per colour channel (PNG supports 16, WebP stops at 8), and files that must open in older desktop software that does not read .webp. Very large images are a fourth, because WebP tops out at 16,383 pixels on either side.
- Use WebP for transparent logos, icons and screenshots on websites, where the smaller file loads faster.
- Keep PNG for editing masters, 16-bit images, and files sent to people whose software may not open WebP.
- Converting WebP to PNG keeps the transparency but usually makes the file bigger, because PNG stores every pixel losslessly.
- To convert PNG to WebP or WebP to PNG, set the Output Format in the PDFixel Image Resizer or Image Compressor. Both run in your browser, so the image is never uploaded.
When to Use JPEG, WebP or PNG
Use WebP for all web applications, blog assets, e-commerce stores, and digital marketing materials. Reserve JPEG for raw camera backups, printing physical photos, or sending files to legacy desktop publishing software.
Keep PNG for graphics you are still editing and for transparent images that have to open in any program. Saving a transparent PNG or WebP as JPEG fills the transparent areas with a solid colour, because JPEG cannot store transparency.
Summary
Converting your digital imagery from JPEG to WebP is one of the easiest ways to slash bandwidth costs and accelerate page loading speeds without sacrificing visual quality.