What Is WebP? The Complete Guide to Google's Image Format
WebP is a modern image format developed by Google that delivers significantly smaller file sizes than JPG and PNG while maintaining equivalent visual quality. Since its introduction in 2010, WebP has become the dominant image format for web performance optimization — but many users and developers still have questions about what it is, how it works, and when to use it.
What Is WebP and Who Created It?
WebP is an image format developed by Google, first released in 2010. It was created as part of Google's broader effort to make the web faster by reducing the amount of data needed to transfer images. The name is a portmanteau of "Web" and "P" (for picture).
WebP is based on technology derived from Google's VP8 video codec — the same technology used to compress video frames in the WebM video format. By applying video compression techniques to still images, WebP achieves compression efficiency that significantly exceeds older image formats like JPEG (developed in 1992) and PNG (developed in 1996).
Google published WebP as an open standard with royalty-free licensing, and all major browser vendors have implemented support. As of 2024, WebP is natively supported in Chrome, Firefox, Safari, Edge, and virtually all modern browsers worldwide.
How WebP Compression Works
WebP supports two compression modes: lossy and lossless.
In lossy mode, WebP uses a technique called predictive coding — the encoder predicts the value of each pixel based on surrounding pixels and only stores the difference (the "residual"), not the full pixel value. This prediction is much more sophisticated than JPEG's discrete cosine transform algorithm. The result is that WebP lossy files are typically 25–34% smaller than JPEG files at equivalent visual quality.
In lossless mode, WebP uses a combination of color transformation, spatial prediction, Huffman entropy coding, and a color cache system. WebP lossless files are typically 26% smaller than equivalent PNG files — offering true lossless compression with better efficiency than PNG.
WebP also supports animated images (replacing GIF and animated PNG) and transparency (alpha channel), making it a versatile single format that can replace JPG, PNG, and GIF in most web contexts.
WebP vs JPG vs PNG: File Size Comparison
The size advantage of WebP is its defining feature. Google's own benchmarks show:
Compared to JPEG: WebP lossy images are 25–34% smaller at equivalent SSIM (structural similarity) quality scores. For a typical web page with 10 product images at 200 KB each (2 MB total), switching to WebP could reduce that to 1.3–1.5 MB — saving 25–35% of image bandwidth on every page load.
Compared to PNG: WebP lossless images are approximately 26% smaller. For a logo that is 150 KB as PNG, WebP lossless would typically be around 110 KB.
For websites serving millions of page views, these savings translate directly to reduced CDN bandwidth costs, faster page loads, and improved Core Web Vitals scores — particularly Largest Contentful Paint (LCP), which Google uses as a ranking signal.
WebP Browser and Application Support
All major modern browsers support WebP natively: Chrome (since 2014), Firefox (since 2019), Safari (since 2020 on macOS Big Sur and iOS 14), Edge (since 2018), and Opera. As of 2024, global WebP browser support exceeds 97% of web users.
However, application support outside of browsers remains inconsistent. WebP files cannot be opened natively in older versions of Windows Photos, macOS Preview (pre-2020), older versions of Photoshop (without plugins), many email clients, most print services, and numerous desktop applications. This is why WebP downloaded from the web often needs to be converted to JPG or PNG for practical use.
For web development and publishing, WebP is now considered safe to use as the primary format. For files intended to be downloaded and used by end users in applications, JPG or PNG may be more practical.
When Should You Use WebP?
Use WebP when publishing images on websites where performance matters. Converting your image library from JPG/PNG to WebP before uploading to your CMS is one of the highest-impact optimizations for page speed — Google Lighthouse, PageSpeed Insights, and GTmetrix all flag "serve images in next-gen formats" as an optimization recommendation.
Use JPG or PNG instead of WebP when: you need files that open in non-browser applications (image editors, print services, messaging apps), when you are sharing images with users who may be on older systems, or when you are building image archives meant to outlast format support.
The practical workflow for most web publishers: keep JPG or PNG as your master/source files, convert to WebP for web delivery, and serve the WebP version to users. This gives you both the performance benefits of WebP and the universal compatibility of JPG/PNG for offline use.
Frequently Asked Questions
Is WebP better than JPG?
For web use, yes — WebP produces 25–34% smaller files than JPG at equivalent quality. For general compatibility (applications, email, print), JPG is more universally supported.
Can I open WebP files on Windows?
Recent versions of Windows 11 support WebP natively. Older Windows versions may need a codec extension or an application that supports WebP (like Chrome or the WebP codec from the Microsoft Store).
Does WebP support transparency?
Yes. WebP supports full alpha channel transparency, like PNG. This makes it suitable for logos and icons on the web where transparency is needed.
Should I convert my website images to WebP?
Yes, if performance is a priority. Converting images to WebP reduces page weight by 25–35%, improving load speed and Google PageSpeed scores. All modern browsers support it.
Is WebP lossless or lossy?
Both. WebP supports both lossy and lossless compression modes. Lossy WebP is smaller than JPG; lossless WebP is smaller than PNG.