WebP produces files 25 to 35 percent smaller than PNG for the same image, and it keeps the transparent background PNG is famous for. That single fact explains why Google built WebP and why most modern websites now serve it. PNG's counter-argument is reach: it opens in every program ever written, including software that has never heard of WebP. So the choice is not about which format is technically superior, because WebP plainly is. It is about whether you are optimising for a modern website or for guaranteed compatibility everywhere. This guide compares the two in depth across compression, transparency, quality modes, browser support, animation, and page speed, then gives you a clear rule for choosing.

What WebP is and why Google made it

WebP is an image format Google released in 2010, built on compression technology from its VP8 video codec. The goal was blunt: make web images smaller so pages load faster. Google had the data to know that images dominate page weight, and that shaving a third off every image would measurably speed up the web. WebP was designed from the start to replace three formats at once, matching PNG's transparency, JPG's photographic compression, and GIF's animation in a single container. That ambition is why it can do things PNG cannot.

What PNG is and why it endures

PNG arrived in 1996 as a patent-free replacement for GIF, using lossless DEFLATE compression and adding a full alpha channel. It became the standard for logos, icons, screenshots, and any graphic needing a see-through background. Nearly three decades of universal support is its moat. Every browser, operating system, email client, office suite, and image editor reads PNG without setup. When an image absolutely must open somewhere unknown, PNG is the format that never fails.

File size: WebP wins clearly

WebP compresses better than PNG in essentially every scenario. For a typical logo or UI graphic with transparency, expect a 25 to 35 percent reduction moving from PNG to WebP losslessly. Push into WebP's lossy mode and the saving grows dramatically, often 60 to 70 percent, while still keeping the alpha channel. PNG has no lossy option at all, so it cannot compete on the low end. Across a site with dozens of image assets, that difference compounds into hundreds of kilobytes per page load.

The gap comes from smarter compression. PNG's DEFLATE algorithm is a general-purpose method borrowed from ZIP, good at finding literal repetition. WebP uses predictive coding built specifically for images, guessing each block from its neighbours and storing only the difference. That image-aware approach finds savings DEFLATE cannot see, which is why a format from 2010 beats one from 1996 so consistently.

Transparency: both have it, WebP does more

Unlike JPG, both formats carry a full alpha channel, so a logo stays see-through in either. But WebP adds something PNG cannot match: transparency in lossy mode. PNG's transparency only comes with lossless compression, so a semi-transparent graphic must be stored at full lossless weight. WebP lets you have a transparent background and aggressive compression at the same time, which is exactly what a heavy PNG logo needs. For UI assets and product cutouts that must stay transparent while weighing less, this combination is WebP's strongest argument.

Quality: lossless and lossy modes

WebP offers both modes, which makes it flexible in a way PNG is not:

Lossless WebP matches PNG exactly, pixel for pixel, while producing a smaller file. There is no quality trade-off, only a size win.
Lossy WebP discards detail like JPG does, shrinking files far further, and unlike JPG it can still hold transparency.

PNG only offers lossless, which is why it stays large. If you need a perfect copy, lossless WebP gives it to you smaller. If you can accept invisible loss, lossy WebP gives you a fraction of the size. Either way there is a WebP setting that beats the PNG.

Browser and software support

This is PNG's only real advantage, and it is narrowing. Every modern browser supports WebP, including Chrome, Firefox, Safari, and Edge, so on the open web the compatibility question is essentially settled. The gaps live elsewhere: some older desktop software, certain email clients, older Office versions, and legacy platforms still reject WebP. Upload forms are the other trap, since many accept only JPG and PNG and will refuse a WebP file outright.

So the honest summary is that WebP is safe for your website and risky for files you hand to unknown systems. PNG remains the universal fallback for anything leaving your control.

Animation: WebP replaces GIF too

One capability PNG simply lacks is animation. Standard PNG holds a single frame, and while the APNG extension exists, support has always been inconsistent. WebP supports animation natively with full alpha, producing files far smaller than the equivalent GIF while showing millions of colours instead of GIF's 256. If you are choosing between formats for a short looping graphic, WebP beats both PNG and GIF decisively.

Why WebP speeds up websites

Page weight feeds directly into Largest Contentful Paint, one of Google's Core Web Vitals and a confirmed ranking signal. Images are usually the heaviest thing on a page, so cutting each one by a third has a measurable effect on load time, on that LCP score, and on bounce rate. Faster pages also convert better, which is why performance work pays twice.

The practical pattern most sites use is progressive: serve WebP to browsers that support it and fall back to PNG or JPG for the rest. Modern HTML handles this automatically with the picture element, and most content management systems and image services do it for you. You get the speed win without breaking anything for older clients.

When to use each format

Use WebP for website images, especially logos and icons with transparency, where smaller files mean faster pages.
Use WebP when you need transparency plus small size, since it is the only common format offering both.
Use PNG when the image must open in any program, including old software and email clients.
Use PNG for upload forms and systems that explicitly list accepted formats and omit WebP.
Use PNG as your archival master, since universal support matters more than size for a file you keep forever.

How to convert PNG to WebP

Converting takes no install. Open our converter, add your PNG, and choose the option that keeps transparency, which exports WebP. Processing runs locally through the HTML5 Canvas API, so nothing uploads, and you can batch several files at once. The transparent background survives intact while the file gets meaningfully lighter. The full walkthrough is in the PNG to WebP guide.

What about AVIF?

Worth knowing for context: AVIF is a newer format that compresses even better than WebP, often another 20 percent smaller, and it also supports transparency and animation. Browser support is now good but slightly behind WebP, and software support is further behind still. For most sites today, WebP is the pragmatic choice with the best balance of savings and support, with AVIF worth watching as adoption grows. PNG remains the fallback under both.

The verdict

WebP wins on the technical merits comprehensively: smaller files, transparency in both lossless and lossy modes, animation, and full modern browser support. PNG wins on one thing that still matters, which is opening absolutely everywhere without question. Use WebP for your website and PNG for anything you send into the unknown, and serve WebP with a PNG fallback when you want both. For the wider format picture, the PNG vs JPG guide covers where photographs fit in.

Real-world size examples

Abstract percentages help less than actual numbers, so here is what the gap looks like on typical assets:

A 500 by 500 pixel logo with transparency: around 45KB as PNG-24, around 30KB as lossless WebP, and under 12KB as lossy WebP with the alpha channel intact.
A full-width hero graphic with soft shadows: often 400KB or more as PNG, roughly 260KB as lossless WebP, and well under 100KB as lossy WebP.
A UI icon set of twenty small graphics: the whole set can drop from around 200KB to 130KB losslessly, before any lossy tuning.

Multiply the hero example across a dozen pages and the saving becomes seconds of load time on a slow connection, which is exactly the kind of difference Core Web Vitals measures.

Converting an existing PNG library

Most sites do not start clean; they have hundreds of PNGs already deployed. Three approaches work, depending on your setup. If your site runs on a modern framework or CMS, the image pipeline probably converts and serves WebP automatically, so you change a setting rather than files. If you use a CDN or image service, most offer automatic format negotiation, delivering WebP to browsers that accept it and PNG to those that do not, from the same source file. And if you are managing files by hand, batch converting the assets and updating the references works, though it is the most labour.

Whichever route you take, keep the original PNGs. They are your masters, and you may need them for a system that rejects WebP later.

Common WebP mistakes to avoid

A few traps catch people moving to WebP:

Converting your archival masters: convert copies for delivery and keep the PNG originals, since WebP support is narrower in desktop software.
Using lossy WebP on text graphics: lossy compression smudges sharp letters just as JPG does. Use lossless WebP for screenshots and text-heavy images.
Skipping the fallback: serving WebP with no PNG or JPG alternative breaks the image for older clients and some email contexts.
Sending WebP to upload forms: many accept only JPG and PNG and will reject the file outright.

None of these are reasons to avoid WebP. They are reasons to use it where it belongs, which is delivery to modern browsers, while keeping PNG for masters and for anything leaving your control.

How browsers actually choose the format

Serving two formats sounds complicated, but the mechanism is simple and automatic. Every browser sends an Accept header with each image request, listing the formats it understands. A server or CDN reads that header and returns WebP to a browser that advertises support, or the PNG to one that does not, from the same URL. In HTML you can do the same thing explicitly with the picture element, listing a WebP source first and a PNG fallback second; the browser picks the first one it can read and ignores the rest. Either way, no visitor ever sees a broken image, and modern browsers quietly get the smaller file while older ones get the compatible one.

Frequently asked questions

Is WebP better than PNG?

Technically yes. WebP files are 25 to 35 percent smaller, keep transparency, and add lossy and animation modes PNG lacks. PNG wins only on universal compatibility.

Does WebP support transparency like PNG?

Yes, and further. WebP keeps an alpha channel in both lossless and lossy modes, while PNG only offers transparency with lossless compression.

How much smaller is WebP than PNG?

Typically 25 to 35 percent smaller losslessly, and 60 to 70 percent smaller in lossy mode while still holding transparency.

Do all browsers support WebP?

Every modern browser supports WebP, including Chrome, Firefox, Safari, and Edge. Some older desktop software and upload forms still reject it.

Which formats support transparency and animation?

WebP does both. PNG has transparency but no reliable animation, and GIF animates but is limited to 256 colours with crude transparency.

Is WebP or PNG better for a website?

WebP, for speed. Smaller files improve Largest Contentful Paint, a Core Web Vitals ranking signal. Serve a PNG fallback for older clients.

Should I use WebP or AVIF?

WebP, for now. AVIF compresses about 20 percent better but has narrower support, so WebP is the pragmatic balance of savings and compatibility today.

Can I upload a WebP file to a form?

Often not. Many upload forms accept only JPG and PNG, so convert to one of those when a system lists its accepted formats and omits WebP.

Should I convert my existing PNG files to WebP?

Convert copies for delivery, not your masters. Keep the original PNGs, since WebP support is narrower in desktop software and upload forms.

Is lossy WebP good for screenshots with text?

No. Lossy compression smudges sharp letters, exactly as JPG does. Use lossless WebP for text-heavy graphics and screenshots.

Do I still need a PNG fallback with WebP?

For maximum safety, yes. Modern browsers all read WebP, but older desktop software, some email clients, and many upload forms still do not.

How does a browser know whether to load WebP or PNG?

Through the Accept header it sends with every request, which lists supported formats. Servers and CDNs read it and return WebP or the PNG fallback automatically.