What Is WebP?
WebP is a modern image format developed by Google, first released in 2010. It was designed to replace JPEG and PNG by offering superior compression while maintaining comparable visual quality. The format derives from the VP8 video codec's intra-frame compression technology and was later extended to support lossless compression, transparency, and animation.
The name stands for "Web Picture," and the format's primary design goal was to reduce the bandwidth cost of images on the web. Images are typically the largest contributor to page weight, and WebP's improved compression directly translates to faster page loads and lower data costs for users on mobile connections.
How WebP Compression Works
WebP uses different techniques for lossy and lossless compression.
For lossy WebP, the encoding is based on block prediction similar to the approach used in modern video codecs. The image is divided into blocks, and each block is predicted from its neighbors. Only the difference between the prediction and the actual block data is stored. This prediction-based approach is significantly more efficient than JPEG's DCT-based approach, especially for images with large uniform areas.
For lossless WebP, the format uses a combination of techniques including palette images, backward reference coding (similar to LZ77), and color transform coding. Google's research showed that lossless WebP files are typically 26% smaller than equivalent PNGs.
WebP also supports alpha transparency in both lossy and lossless modes. In lossy mode, the alpha channel can be stored losslessly while the color data is compressed with lossy methods — a hybrid that works well for images with complex backgrounds and transparent areas.
WebP vs JPEG
JPEG has been the standard for photographic images since the early 1990s. At equivalent visual quality, WebP produces files that are 25-35% smaller than JPEG. This is a substantial saving that adds up significantly across a website with hundreds of product images or a photo gallery.
The compression advantage is most visible in images with complex, natural content like photographs. For very simple images or at extreme compression levels, the difference narrows. At very low quality settings where blocking artifacts dominate both formats, the advantage becomes less consistent.
JPEG has one significant advantage: universal support. Every device, application, and service that handles images understands JPEG. WebP support, while now very broad, is not quite universal — older software and some specialized applications may not handle WebP correctly.
WebP vs PNG
PNG uses lossless compression and supports full alpha transparency, making it the standard for graphics, logos, screenshots, and images where exact pixel values matter. WebP lossless compression produces files about 26% smaller than PNG while maintaining identical pixel-perfect quality.
For images requiring transparency, WebP offers more flexibility. PNG can only store lossless transparent data. WebP can store transparency in both lossy and lossless modes, meaning a WebP file with transparency can be much smaller than an equivalent PNG without any quality loss in the transparent regions.
The main case where PNG still outperforms WebP is rendering speed. Some image processing pipelines, graphic design tools, and content management systems have highly optimized PNG handling built over decades. WebP decoding is generally fast but may have higher overhead in certain specialized contexts.
Browser and Platform Support
As of 2024, WebP is supported by all major browsers: Chrome (since 2010), Firefox (since 2019), Safari (since 2020), and Edge. Mobile browsers on Android and iOS both support WebP. This represents effectively universal browser support for web use cases.
However, browser support is not the complete picture. Many image editing applications, older versions of macOS Preview, Windows Photo Viewer (pre-2019), and various specialized tools do not natively support WebP. If you need images that open without issues in any application a user might have, JPEG or PNG remain safer choices.
Operating system support has improved significantly. macOS 11 Big Sur and later handle WebP in Preview and Quick Look. Windows 10 with the WebP Image Extensions from the Microsoft Store (or Windows 11 by default) supports WebP in Photos and other built-in apps.
When to Use WebP
WebP is the right choice for images displayed on websites and web applications where file size and load time matter. Product images in e-commerce, blog photos, background images, and any image that will be served over HTTP are excellent candidates for WebP conversion.
The format is particularly valuable for mobile-first use cases. Mobile users on cellular connections benefit directly from the smaller file sizes, and mobile browsers have supported WebP for several years.
WebP is not ideal for images that need to be opened in arbitrary software, sent to print services, used as source files for editing, or archived for long-term preservation. For these use cases, JPEG or PNG remain more universally compatible. A practical approach for many workflows is to store master copies in JPEG or PNG and convert to WebP only for web delivery.