What Is WebP? Complete Guide to
Google's Image Format

What Is WebP?

WebP (pronounced "weppy") is an image format created by Google in 2010 to make web pages load faster. It was designed as a direct replacement for JPG, PNG, and GIF — combining the strengths of all three formats into one. WebP supports lossy compression (like JPG), lossless compression (like PNG), transparency (like PNG), and animation (like GIF), all while producing significantly smaller files.

The format is based on the VP8 video codec, which Google acquired when it purchased On2 Technologies in 2010. Google took the intra-frame coding technology from VP8 (the part that compresses individual video frames) and adapted it for still images. The lossless mode, added in 2012, uses an entirely different algorithm based on transform coding, entropy coding, and a palette-based approach.

As of 2026, WebP has become the dominant image format on the web. Google Images, Facebook, Instagram, Amazon, eBay, Wikipedia, YouTube, and millions of other websites serve their images in WebP format. When you right-click and save an image from most modern websites, you'll get a .webp file — not the familiar .jpg you might expect.

How WebP Compression Works

WebP uses fundamentally different compression approaches for its lossy and lossless modes. Understanding how each works explains why WebP achieves better compression than older formats.

Lossy Mode (VP8-Based)

WebP's lossy compression is derived from the VP8 video codec's intra-frame prediction. Unlike JPG, which uses the Discrete Cosine Transform (DCT) on fixed 8×8 pixel blocks, WebP uses block prediction combined with DCT on variable-size blocks. Here is how it works:

1. Macro-block division — the image is divided into 16×16 pixel macro-blocks (compared to JPG's 8×8). Larger blocks mean less overhead for smooth areas.
2. Intra prediction — each block is predicted from already-decoded neighboring blocks using one of four prediction modes (horizontal, vertical, DC, TrueMotion). The encoder stores only the difference between the prediction and the actual pixels.
3. DCT and quantization — the residual (prediction error) is transformed using the DCT and then quantized. Because prediction removes most of the redundancy, the residuals are small and compress very efficiently.
4. Entropy coding — WebP uses arithmetic coding (specifically, a variant of boolean arithmetic coding from VP8), which is more efficient than JPG's Huffman coding. This alone saves several percent compared to baseline JPEG.

The combination of better prediction, larger block sizes, and superior entropy coding is why WebP lossy images are 25–35% smaller than JPG at the same visual quality. The quality parameter ranges from 0 (smallest file, lowest quality) to 100 (largest file, highest quality), similar to JPG.

Lossless Mode

WebP lossless compression uses an entirely different algorithm from the lossy mode. It was introduced in 2012 and is designed to compete with PNG. The lossless compressor uses several advanced techniques:

• Spatial prediction — each pixel is predicted from up to 13 different spatial prediction modes based on neighboring pixels. The encoder picks the best mode for each region.
• Color transform — WebP decorrelates the RGB color channels by predicting green from red, and blue from green and red. This reduces the entropy of the color data significantly.
• Subtract-green transform — a simplified color decorrelation that subtracts the green channel from red and blue, exploiting the fact that natural images have high correlation between channels.
• Palette-based coding — for images with 256 or fewer unique colors, WebP automatically switches to an indexed palette mode similar to PNG-8 but with better compression.
• LZ77 backward references — the encoder finds repeated pixel patterns and replaces them with references to earlier occurrences, similar to how ZIP compression works.
• Huffman coding — the final compressed stream uses optimized Huffman tables for maximum compression.

The result: WebP lossless images are typically 26% smaller than PNG files of the same image. For images with limited color palettes (icons, logos, simple graphics), the savings can exceed 40%.

Transparency (Alpha Channel)

WebP supports a full 8-bit alpha channel in both lossy and lossless modes. This is a significant advantage over JPG, which has no transparency support at all. In lossy mode, the alpha channel can be compressed either losslessly (preserving exact transparency values) or lossily (for additional file size savings). The lossy alpha option is unique to WebP and is useful when precise transparency boundaries are not critical.

A lossy WebP image with transparency is typically 3x smaller than an equivalent PNG-24 with transparency, making it ideal for web delivery of logos, icons, and UI elements that need transparent backgrounds.

Animation

WebP supports animation using a container format similar to how GIF stores multiple frames. Each frame can use either lossy or lossless compression, and the format supports:

• Variable frame delays (like GIF)
• Full 24-bit color with 8-bit alpha per frame (GIF is limited to 256 colors per frame)
• Lossy compression per frame (GIF is lossless only)
• Inter-frame compression (only encoding the changed pixels between frames)

Animated WebP files are typically 40–90% smaller than equivalent GIFs while supporting millions of colors and smooth transparency. This makes animated WebP the preferred format for short animations, stickers, and looping video clips on the web.

File Size Comparison: WebP vs JPG vs PNG

The primary reason websites adopted WebP is file size savings. Here are real-world comparisons for typical web images:

For a typical web page with 20 images, switching from JPG to WebP saves approximately 500 KB–2 MB per page load. At scale, this translates to significant bandwidth cost savings and measurably faster page load times — which is why Google, Facebook, and Amazon made the switch years ago.

How to Open WebP Files

Opening a WebP file depends on your operating system and the software you have installed. Here is a complete guide for every platform.

Windows

Windows 11: The built-in Photos app and Paint both open WebP files natively. Double-clicking a .webp file should open it in Photos by default. You can also open WebP in Paint and export to JPG via File > Save As.

Windows 10: Support was added via updates in later versions. If WebP files don't open, ensure your system is fully updated. Alternatively, install Google's WebP codec for Windows, which adds WebP support to the Windows Photo Viewer and other applications.

Third-party viewers: IrfanView (free, with WebP plugin), Paint.NET (free, with WebP plugin), and XnView (free) all handle WebP files. These are excellent options for older Windows versions or for batch viewing and conversion.

Mac

macOS Big Sur (11.0) and later: Preview and Quick Look (press Space in Finder) open WebP natively. You can also export to JPG or PNG via Preview's File > Export menu.

Older macOS versions: WebP is not supported natively. Install a third-party viewer like XnView or open WebP files in any web browser (drag the file into Chrome, Safari, or Firefox). For frequent use, consider upgrading to Big Sur or later.

Web Browsers

All modern web browsers support WebP natively. You can open any WebP file by dragging it into your browser window or using File > Open. This works in:

• Chrome — since version 23 (2012)
• Firefox — since version 65 (2019)
• Safari — since version 14 / macOS Big Sur (2020)
• Edge — since version 18 (2018)
• Opera — since version 12.1 (2012)

This is the quickest way to view a WebP file on any computer — just open it in your browser.

Phones and Tablets

iPhone/iPad: iOS 14 and later support WebP in Safari, the Photos app, and Files. Older iOS versions cannot display WebP. If you receive a WebP file on an older device, you'll need to convert it to JPG first.

Android: Android has supported WebP since version 4.0 (2011) for lossy WebP and since version 4.2 (2012) for lossless and transparent WebP. The built-in Gallery app, Google Photos, and all Android browsers display WebP files without issues.

Adobe Photoshop

Photoshop 23.2 (released February 2022) and later versions support WebP natively — you can open, edit, and save WebP files directly. If you have an older version, you'll need a third-party WebP plugin or must convert to JPG/PNG before opening in Photoshop. Convertio.com handles this conversion in seconds.

Common Problems with WebP

Despite its technical advantages, WebP creates real-world headaches for users. These are the most common issues people encounter.

Older Software Can't Open WebP

While all modern browsers support WebP, many desktop applications do not. Older versions of Photoshop (before 23.2), Microsoft Office (before 365 updates in 2023), Lightroom (before 2022), and hundreds of niche applications reject WebP files entirely. This means you may download an image from the web and find that your preferred editing or viewing software cannot open it.

Email Client Incompatibility

Many email clients handle WebP poorly. Some strip WebP attachments, some display them as broken images, and some show a generic file icon instead of a preview. Corporate Outlook installations, older webmail services, and email clients on older devices are the most common offenders. If you need to email images, converting to JPG ensures every recipient can view them.

Social Media Upload Restrictions

Some social media platforms reject WebP uploads in certain contexts. Profile photo editors, event cover images, marketplace listings, and story uploads on various platforms may require JPG or PNG specifically. While this is improving, the safest approach for uploads is still JPG.

Printing Services Don't Accept WebP

Online printing services (photo books, canvas prints, business cards, posters) and local print shops almost universally require JPG, PNG, or TIFF files. WebP is virtually unknown in the printing industry. If you need to print a web image you've saved, converting to JPG is a necessary step.

Maximum Dimension Limit

WebP has a hard limit of 16,383 × 16,383 pixels. This is sufficient for virtually all web and personal photography use, but it falls short for certain professional applications: ultra-high-resolution panoramas, large-format print files, scientific imaging, and detailed maps or satellite imagery can easily exceed this limit. JPG supports up to 65,535 × 65,535 pixels, and PNG has no practical dimension limit.

Lossy WebP Artifacts at Low Quality

At very low quality settings (below 50), WebP lossy images can exhibit a characteristic "plastic" or "wax-like" appearance. The block prediction system produces smoother but less natural-looking artifacts compared to JPG's blocky DCT artifacts. Some photographers and designers find these artifacts more objectionable than JPG's artifacts at equivalent quality levels, particularly on skin tones and textured surfaces.

When to Use WebP

WebP excels in specific scenarios where its advantages matter most:

• Web delivery — any image served on a website, web app, or PWA. This is WebP's primary purpose and where it delivers the most value.
• Bandwidth-constrained environments — mobile apps, areas with slow connections, and applications where data transfer costs are significant.
• Replacing GIF — animated WebP is dramatically smaller than GIF with vastly superior quality (24-bit color vs 256 colors).
• Transparent web graphics — lossy WebP with alpha is far smaller than PNG for images that need both photographic quality and transparency (product photos on transparent backgrounds, for example).

When NOT to Use WebP

There are clear situations where WebP is the wrong choice:

• Email attachments — use JPG for universal compatibility.
• Printing — use JPG (for photos) or PNG/TIFF (for graphics). No printing service accepts WebP.
• Archival storage — use lossless PNG, TIFF, or the original RAW file. WebP's lossy compression discards data permanently, and the format is younger with less long-term track record than JPEG or TIFF.
• Images larger than 16,383 pixels — WebP simply cannot encode images beyond this dimension.
• Workflows with older software — if your editing pipeline involves software that doesn't support WebP, converting to JPG or PNG at the start saves frustration.
• Universal sharing — when you don't know what device or software the recipient uses, JPG is the safest choice.

Convert WebP to JPG

When WebP's compatibility limitations are a problem, converting to JPG is the simplest solution. JPG is the most universally supported image format in existence — every device, application, email client, social media platform, and printing service accepts it without question.

When converting from lossy WebP to JPG, there is a minimal quality reduction because both are lossy formats. However, at high quality settings the difference is imperceptible to the human eye. Convertio.com uses optimized encoding settings to ensure the JPG output looks identical to the WebP original for all practical purposes.

For lossless WebP files, converting to JPG introduces lossy compression for the first time. The resulting JPG will be an excellent-quality approximation, but if you need perfect pixel preservation, consider converting to PNG instead.