PNG to JPG is a one-way change of container. PNG stores pixels losslessly and can store a transparent pixel. JPEG stores a lossy picture and cannot store transparency. People convert PNG to JPEG when a form, a chat app, or a printer asked for JPG, or when a screenshot of a photo is larger than it needs to be. This page does that conversion in the browser. You can also drop a WEBP or a GIF still: each selected file is drawn and encoded as a JPEG. The words on the button say JPG. The file is a JPEG, which is why searches for convert PNG to JPG and PNG to JPEG land on the same job.
Transparent pixels are the detail that surprises people. A PNG logo on a transparent background becomes that logo on white, because the encoder needs a colour for every pixel. If the logo was meant to sit on a dark page, white is the wrong matte. Export again from the tool that made the logo, on the background you actually want, or keep the PNG. The page does not offer a colour picker for the matte. White is the choice, and it is stated here so the result is not a mystery.
Quality is a slider from 40 to 100, starting at 85. The browser's JPEG encoder receives that number divided by 100. Lower values throw away more detail and usually shrink the file. Higher values keep more of the original and can end up larger than the PNG you started with, especially on a flat screenshot, because JPEG is a poor fit for large areas of one colour and for sharp text. If the JPEG is bigger, that is the format telling you to keep the PNG. This slider does not change width or height. For a smaller pixel grid, or for a target size in kilobytes, use the image compressor, which is built for that question.
Batch is the file input with multiple selection. Each image is converted in order. You get a link for each JPEG, and one zip that contains all of them. Names come from the original file name with the extension replaced by .jpg. Matching is case-insensitive, so Photo.PNG and photo.png cannot both claim photo.jpg. The first keeps its base name. The next becomes photo-2.jpg, then photo-3.jpg, and so on. The zip uses stored entries, not a second round of JPEG compression, so the bytes inside the zip are the JPEGs you already previewed. Unzip and you should see a file that starts with the JPEG marker.
The file converter also has a PNG to JPG path among many other pairs. This page is the dedicated one: quality, batch, and zip, and nothing else in the form. If the next step is a document, the JPG to PDF page places each image on its own PDF page. That is a different file. Do not convert to JPEG first if you still need transparency inside the PDF. A PNG can go straight to that PDF tool.
Nothing is uploaded. There is no account and no server-side queue. Very large images are limited by the memory of the tab, not by a quota this site publishes, because the site never receives the file. If the browser cannot decode the image, the note on the form says so and that file is skipped in spirit by the error: fix the file or export it again. Animated GIF frames are not a slideshow here. The still that the browser draws is the still you get. The directory lists the other image tools if this was the wrong conversion.