Convert PNG to JPG

PNG and JPG solve different problems. PNG stores every pixel exactly and supports transparency, which is why screenshots, logos, and diagrams belong in it. JPG discards detail the eye is unlikely to notice in exchange for a much smaller file, which is why photographs belong in it. Converting from PNG to JPG is normally about size, or about a system that refuses to accept anything else.

The conversion has one consequence worth understanding before you run it. JPG has no transparency channel, so a PNG with a transparent background cannot keep it. Something must fill those pixels. Many converters handle this by drawing the image onto an empty canvas and encoding the result, and because untouched canvas pixels are transparent black, the encoder writes them as solid black. That is the reason a logo so often comes back sitting in a black box. Here the background is filled with white first, so the result matches the white page or slide the image is usually going onto.

Choose the destination format with the content in mind. A photograph converts to JPG well and gets substantially smaller. A screenshot of text, a logo, or anything with hard edges and flat colour will show halos and blocking around those edges, because that is precisely the kind of detail JPG is designed to throw away. If the file is already small enough, converting it gains nothing and costs quality permanently.

Conversion happens in your browser. Screenshots often contain more than intended, from window titles to email addresses to open documents in the background, which is a good reason for them not to travel to a server just to change format.