WebP Explained

By Nathan Hays · Updated July 28, 2026

WebP is the format most of the web quietly switched to. It makes noticeably smaller files than JPG or PNG at the same visual quality, it handles transparency, and every major browser displays it. It is also the reason a picture you saved from a website suddenly will not open in your photo editor. This page covers both sides: when WebP is the right target, and when converting away from it is the sane move. The image converter goes both directions on your own device.

What WebP actually is

WebP is an image format developed by Google and released as an open, royalty-free standard. Its lossy compression borrows techniques from video encoding, which turns out to be a good fit for still images: instead of only describing each block of pixels on its own, the encoder can predict a block from its neighbors and store just the difference. Predicting well means storing less, and storing less means smaller files.

Unusually, WebP is really two formats sharing one file extension. Lossy WebP targets photographs and behaves like a more efficient JPG. Lossless WebP targets graphics and behaves like a more efficient PNG, including full alpha transparency. A single .webp file may be either, which is why WebP can replace both of the older formats rather than just one.

How much smaller, honestly

The number quoted by Google, and the one most people reproduce in their own testing, is that lossy WebP runs roughly 25 to 35 percent smaller than an equivalent-quality JPG. Lossless WebP typically lands meaningfully below PNG for the same graphic. Those are useful planning figures rather than guarantees, and it is worth knowing where they break down:

• Detailed photographs benefit most. Lots of texture gives the encoder plenty to work with.
• Already-small images benefit least. Below a few kilobytes, format overhead dominates and the saving can vanish.
• Already-compressed JPGs give a smaller-looking win, because you are re-encoding an image whose fine detail was removed once already.
• Flat graphics with transparency often show the biggest win of all, because lossless WebP handles them far more efficiently than PNG.

The honest way to find your own number is to convert a representative handful of your own images and compare. The converter shows the original and converted size on every row, so a five-image sample takes about a minute.

Where WebP works and where it does not

Inside a browser, WebP is settled: every major current browser displays it, and you can serve it directly without a fallback for practical purposes. Search engines index WebP images normally. Content management systems and static site generators overwhelmingly support it.

Outside the browser is where friction remains. Some older desktop photo editors, older office software, print shop upload tools, and a surprising number of web forms still accept only JPG and PNG. Operating systems have largely caught up, but "largely" is not "always", and if you are sending a file to someone else's workflow you cannot inspect, JPG remains the format that never causes an argument. That mismatch is precisely why WebP to JPG is one of the most common conversions people search for.

When WebP is the right choice

• Photos and hero images on your own site. Smaller files load faster, and page speed feeds into both user experience and search performance.
• Graphics with transparency on a site. Lossless WebP often beats PNG substantially while keeping the alpha channel intact.
• Image-heavy pages on mobile connections. A 30 percent cut across twenty images is the kind of change users actually feel.
• Anywhere you already control the HTML. If you can pick the file the page requests, you can pick WebP.

When to avoid WebP

• Files you email or hand to other people. You cannot see what software is on the other end.
• Long-term personal archives. JPG's universality is a feature when the timescale is decades.
• Print submissions. Print workflows are conservative and usually specify JPG, TIFF, or PDF.
• Upload forms with a fixed accept list. If the form says JPG or PNG, believe it.
• Master copies you will keep editing. Lossy WebP is still lossy; work from a lossless original.

WebP versus AVIF

AVIF is the newer contender and generally produces even smaller files than WebP at comparable quality, with support for a wider range of color. The trade-offs are that AVIF encoding takes noticeably longer, and software support outside browsers is thinner still. For most sites WebP is the pragmatic default and AVIF is the optimization you reach for on the images that matter most. If you want the smallest possible file and you control the page, AVIF is worth the extra encoding time; if you want a format that is fast to produce and universally displayed in browsers, WebP is it. Our format guide lines all of them up side by side.

Converting to and from WebP here

This converter creates WebP using your browser's own encoder, so the work happens on your device and nothing is uploaded. Choose WebP as the output format and the quality slider controls the trade-off exactly as it does for JPG; the default 90% is a sensible starting point for photographs. Reading a WebP file works the same way, using the browser's built-in decoder.

One caveat worth knowing: the web standard says that if a browser is asked to export a format it cannot produce, it falls back to PNG rather than failing. Every current major browser exports WebP natively, but if you are on something unusual and the downloaded file is unexpectedly large, check its extension.

Common jumps from here: JPG to WebP for putting photos on a site, and WebP to JPG for making a downloaded image open everywhere.

Common questions

Keep reading

• JPG vs PNG: when each format wins
• Image size vs quality: what actually shrinks a file
• Converting for email, web, print, and social
• The full image format guide
• All guides and converters