What Is a WebP File? Google’s Image Format Explained

You download an image, go to open it, and your software shrugs. The extension says .webp and nothing on your computer seems to want it. That moment is how most people meet WebP — not as a feature, but as an obstacle.

What It Actually Is

WebP is an image format Google released in 2010 with a simple goal: replace JPG and PNG with one format that beats both on file size. Unusually for a format that ambitious, it mostly succeeded.

It does this by borrowing from video compression. JPG was designed in 1992 for still photographs; WebP’s lossy mode is built on techniques from the VP8 video codec, which predicts what a block of pixels will look like based on its neighbours and stores only the difference. Less data to store means a smaller file at the same visual quality.

The Three Things It Does That JPG Cannot

Transparency. JPG has no alpha channel at all — a logo on a transparent background has to be a PNG. WebP supports transparency in both its lossy and lossless modes, which means a transparent logo can be a fraction of the PNG’s size.

Animation. Animated WebP replaces animated GIF and is dramatically smaller. A GIF is limited to 256 colours and compresses poorly; a WebP animation has full colour and often lands at a quarter of the size.

Lossless mode. WebP can compress without discarding any data, like PNG, and typically produces files around 25% smaller than PNG for the same image.

How Much Smaller, Really

The honest answer is: it depends on the image, and the commonly quoted figures are optimistic. For typical photographs, a WebP at visually equivalent quality lands roughly 25–35% smaller than a JPG. For flat graphics and screenshots, lossless WebP against PNG saves a similar proportion.

The savings are real but not transformative. Where WebP genuinely changes things is animation, where the gap against GIF is large, and transparency, where it gives you an option JPG never had.

Where It Still Causes Trouble

Browser support has not been the problem for years — every current browser displays WebP. The friction is elsewhere:

• Desktop software. Older image editors, office suites and print workflows may refuse a .webp file outright.
• Upload forms. Plenty of sites still accept only JPG and PNG, so a WebP saved from the web has to be converted before it can be re-uploaded.
• Print. Professional print workflows run on TIFF and PDF. WebP has no place there.

This is why “how do I convert WebP to JPG” is such a common question. The format is fine; the surrounding tooling has not caught up everywhere.

When to Use WebP, and When Not To

Use it for images on your own website, where you control the pipeline and the saving goes straight into page-load time. Use it for animations that would otherwise be GIFs. Use it for transparent graphics that would otherwise be large PNGs.

Do not use it as your archive format — keep the original. Do not use it for files other people will need to open in unknown software. Do not use it for anything going to print.

Opening and Converting

Every modern browser opens a WebP: drag the file into a browser tab and it displays. To get it into a format other software accepts, convert it to JPG for photographs or PNG if the image has transparency that matters.

One thing worth knowing: converting WebP to JPG is a lossy-to-lossy conversion. The WebP already discarded data; re-encoding as JPG discards more. For a single conversion this is invisible, but repeatedly converting the same image back and forth will visibly degrade it. Convert once, from the best source you have.

WebP Against the Alternatives

• vs JPG — smaller at the same quality, plus transparency and animation. JPG wins only on universal compatibility.
• vs PNG — around 25% smaller losslessly, with the same transparency. PNG wins on compatibility.
• vs AVIF — AVIF compresses better still, but WebP has wider software support and encodes faster.

WebP occupies a sensible middle: clearly better than what it replaces, clearly better supported than what might replace it.