Is WEBP always smaller for a static GIF?

Usually yes, but it is not guaranteed. WEBP's lossless mode stores the same image in less space than PNG in most cases. Its lossy mode produces far smaller files but can introduce visible mess on sharp edges and flat colour areas. On simple low-colour graphics the gap between PNG and WEBP narrows and PNG can occasionally come out ahead; for files that matter, producing both outputs and comparing them is the safest approach.

Is there a difference between them in transparency quality?

Both support an alpha channel and can store smooth opacity transitions per pixel, so in capability they are equal. But because the source GIF's transparency is binary — a pixel is either fully transparent or fully opaque — jagged edges carry over unchanged whichever format you convert to. Getting soft edges requires regenerating the image or working the edges by hand; the format choice will not solve it.

Does lossy WEBP make sense for a static GIF?

Usually not. GIFs typically carry low-colour, sharp-edged graphic content, and lossy compression produces halos around edges and blotches in flat areas on that kind of content. On top of that, adding a second lossy pass to an image that has already been reduced to 256 colours compounds the damage. If the GIF was produced from photographic content, lossy WEBP is worth considering, but for graphic content staying in lossless mode is the right call.

Which is safer for compatibility?

PNG is universal in practice; every browser, every operating system, every editor and nearly every corporate system accepts PNG. WEBP now has very broad support on the browser side and modern operating systems open it too, but some older desktop programs, prepress tools and corporate upload forms may still reject it. If you do not know where the file is going, PNG is the safer choice.

For a Non-Animated GIF: PNG or WEBP?

Let's establish the common ground first

When converting a static GIF, both PNG and WEBP are reasonable targets, and the choice is subtler than you might expect. Both have a lossless mode, both carry an alpha channel, and both operate free of GIF's 256-colour limit.

But before we get into the comparison, there is a fact that applies to both options: whichever you choose, what was lost in the GIF does not come back.

When that GIF was created, the source image was reduced to 256 colours; the discarded tones are permanently gone. Banding and dithering patterns survive intact in both formats. Likewise, the jagged edges produced by GIF's binary transparency carry over — neither PNG nor WEBP smooths them. Both alpha channels can produce soft transitions, but neither can read information that does not exist.

So this comparison is not about quality. It is about file size and compatibility.

File size

Lossless WEBP is usually smaller than PNG. Storing the same image, WEBP's lossless compression algorithm works more efficiently than PNG's DEFLATE in most cases. This is WEBP's most concrete advantage.

The word "usually" matters, though. On simple low-colour graphics with large flat areas the gap narrows, and on some files PNG comes out ahead. The dithering pattern so common in GIFs strains both formats' compression, because a speckled pattern behaves like noise rather than repeating structure.

Practical advice: if file size genuinely matters to you, produce both outputs and compare them. This is a question of measurement, not guesswork.

Lossy WEBP is far smaller but usually the wrong choice. GIFs typically carry sharp-edged, low-colour graphic content. Lossy compression produces halos around edges and blotches in flat colour areas on that content. On top of that, adding a second lossy pass to an image already reduced to 256 colours stacks the damage. If the source GIF came from photographic content, lossy WEBP is worth considering, but for graphic content stay in lossless mode.

Compatibility

PNG is clearly ahead here.

PNG is universal in practice. Every browser, every operating system, every image editor, every office program and nearly every corporate upload form accepts PNG. If you do not know who you are handing the file to, PNG will never cause trouble.

WEBP's support is broad but not universal. On the browser side it has reached a level of ubiquity you could call standard, and modern operating systems open it natively. Against that, some older desktop programs, prepress tools, email clients and corporate systems can still reject WEBP.

This is the comparison's most practical distinction: WEBP is more efficient, PNG is safer.

Transparency

In capability the two are equal. Both PNG and WEBP carry an alpha channel and can store 256 distinct levels of opacity per pixel. Soft edges, semi-transparent shadows, glass effects — all possible in both.

The difference is that WEBP can support transparency in its lossy mode too. That gives WEBP a serious size advantage on transparent images with photographic content. But since you would not be going to lossy mode with GIF-sourced files anyway, this advantage rarely comes into play here.

Once more, for emphasis: the jagged edges inherited from the source GIF survive unchanged in both formats. If you want soft edges, regenerate the image from its original source or convert to PNG and work the edges by hand in an editor.

Decisions by scenario

Publishing on a website: WEBP. The size gain feeds straight into page speed and browser support is sufficient.

Editing the image: PNG. Every editor opens it without trouble and it produces no surprises in layer and channel operations.

Uploading to an institution, a form or a system: PNG. The odds of acceptance are far higher.

Documentation or presentation images: PNG. Office programs and document systems always handle PNG correctly.

Archiving hundreds of files: Lossless WEBP. The size gain becomes meaningful in aggregate, but think about what software you will use to open the archive years from now.

As an email attachment or in a newsletter: PNG. Email clients lag browsers on format support.

A practical approach

For most users, a solid default is this: convert the GIF to PNG, because it causes trouble nowhere and drops straight into an editing workflow. If you have a purpose where size genuinely matters, such as web publishing, keep the PNG as your working file and produce the published version as lossless WEBP.

This two-stage approach is exactly the logic that is standard in professional workflows: a compatible, flexible working format and a delivery format produced as needed.

In summary

Lossless WEBP is usually smaller, PNG is always safer. In transparency capability the two are equal, and neither fixes the jagged edges the GIF left behind. WEBP for web publishing, PNG as the sensible default for everything else. Do not use lossy WEBP on graphic-content GIFs; the size gain is not worth the mess around the edges.