WebP is a genuinely better-engineered format than JPG in most technical respects — smaller files, support for both lossy and lossless compression, and a working transparency channel that JPG never had. None of that helps if the specific piece of software you’re trying to use it in simply doesn’t know what a WebP file is, which is a more common situation than the format’s near-universal browser support might suggest.
The gap between browser support and everything else
It’s easy to assume that because WebP displays correctly on practically every website you visit, it must be broadly supported everywhere. Browser support is indeed close to universal at this point — but browsers are a small slice of the software that handles images. Email clients, older or more specialized photo editors, many business and office applications, printing services, and plenty of web upload forms were built around the assumption that images would be JPG or PNG, and either never added WebP support or only recently started recognizing it, leaving a lot of currently-installed software still unable to open it.
The result is a specific, recurring annoyance: you find an image on a website, save it for later use, and discover the .webp file won’t open in whatever you actually need it for — attaching to an email, uploading to an older system, sending to a printer.
What conversion actually does, and what it costs
Converting WebP to JPG means decoding the WebP file’s image data back into raw pixels, then re-encoding that pixel data using JPG’s lossy compression method. If the original WebP was itself saved in lossy mode — the typical case for photographic content — this conversion introduces a second round of lossy compression on top of the first, causing a small amount of additional quality loss. In practice, at a sensible JPG quality setting (this tool defaults to 85), that additional loss is rarely something you’d notice without zooming in and comparing pixel-for-pixel against the original. If the WebP was saved losslessly, you’re starting from an exact copy of the source image, so the conversion’s only quality cost is whatever JPG’s own compression introduces — the same cost you’d pay converting any clean source image to JPG.
The one thing that doesn’t survive the conversion at all is transparency. WebP supports an alpha channel; JPG fundamentally does not. If your WebP image has transparent areas — a logo or icon on a transparent background is the most common case — converting to JPG flattens those areas onto a solid background (white, by default), permanently losing the transparency. If that matters for your use case, converting to PNG instead preserves it, at the cost of a typically much larger file.
Why JPG, specifically, as the target
JPG isn’t the most space-efficient choice — WebP itself, or PNG for graphics, can often produce comparable or better results. JPG’s advantage is pure compatibility: it’s one of the oldest and most universally implemented image formats in existence, supported by essentially every device, browser, editor, and upload form built in the last two decades. When the actual problem is “this file won’t open somewhere,” compatibility is the thing you’re solving for, and JPG remains the safest default for that specific job — more so than WebP, and more practical than PNG for ordinary photographic content where transparency doesn’t matter.