Where WebP files come from and why they need to be PDF
You rarely create a WebP on purpose. You get one by saving an image from a website: an order confirmation, a shipping label, a product page you want to keep for a warranty claim, a boarding pass shown as an image, or a diagram from documentation. Then an accountant, an insurer or a form upload asks for a PDF and refuses the .webp. This page turns one or more of those saved images into a single PDF without sending them anywhere.
Decoding and re-encoding
The browser decodes WebP natively, so both lossy and lossless files are accepted. Each image is drawn on a canvas at its own pixel size, converted to JPEG at quality 92 and placed on a page with matching dimensions. Most WebP files from the web are already lossy at moderate quality, so this is a second lossy pass. In practice it is invisible for receipts and screenshots, but it is worth knowing: if the site served an aggressively compressed 50 KB WebP, the PDF page will carry those artifacts plus a little more. The output cannot be sharper than the source.
Transparency and animation
WebP can carry an alpha channel, and logos or product cutouts saved from shops frequently do. JPEG cannot, and the canvas paints transparent areas black when it exports JPEG. A product image on a transparent background will therefore sit on a black page. Flatten it first: run it through WebP to JPG, which produces an opaque image you can check, then build the PDF from that. Animated WebP is treated as a still and only the first frame is used.
Typical sizes
A 1200 by 1600 WebP receipt of 90 KB typically becomes a page of 250 to 450 KB, because JPEG at 92 is a less efficient encoder than WebP at the quality the site used. Five such pages give a PDF around 1.5 to 2 MB. If that seems backwards, it is: the PDF is bigger than the sum of the WebP files. The goal here is a format other people accept, not a smaller one. To keep the PDF small, downscale images that are larger than they need to be with the compress and resize tool before converting; a receipt does not need more than about 1500 pixels on its long side to stay legible. All figures are typical, not guaranteed.
Keeping records that hold up
For a warranty or a dispute, what matters is that the document is complete and legible. Capture the whole page rather than a fragment, keep the order number and date visible, and put pages in chronological order when you add them, because the PDF keeps the order you chose. Crop away browser chrome and unrelated sidebars with the crop tool so the page shows only the record itself. The PDF has no text layer, so the recipient cannot search it, but they can read and print it in any viewer.
Limits and privacy
Because everything happens in your browser, there is no upload, no account and no file size quota, but there is a memory limit set by your device. A handful of web images is trivial; a hundred high resolution product photos may fail on a phone. The download is always named images.pdf and contains only images. Metadata that the site may have embedded in the WebP is discarded on the way through the canvas.