Convert JPG to PNG

This conversion is worth doing for two reasons and neither is the one people usually have in mind. The first is editing: PNG loses nothing on each save, so an image about to be cropped, adjusted and exported several times will not accumulate damage the way a JPG does. The second is compatibility — some design tools, print workflows and upload forms want PNG specifically, and there is no arguing with a form.

The reason this conversion is often done and should not be is the word lossless. Converting a JPG to a PNG does not repair it. The detail your camera or your last export threw away is gone, and PNG simply stores the damaged picture very faithfully. If a better original exists anywhere — the camera roll, the original export, the file before it went through a messaging app — convert that instead.

PNG supports transparency; your JPG has none; the result is an opaque image in a format that could have held some. Cutting a background out is editing work, and no conversion does it. If that is what you came for, you need a background remover first and then a PNG to keep the result in.

Five to ten times is ordinary for a photograph, because PNG is a poor fit for continuous tone — it compresses by finding repetition, and a photograph has almost none. If size matters and you only need the image to open somewhere, WebP does the same job at a fraction of the space and is read by every current browser.

Almost every reason to convert a JPG to PNG — editing without further loss, needing a format an editor accepts, wanting no more generational damage — is also served by WebP lossless, which Google measured at about a quarter smaller than an optimised PNG of the same picture. If the destination is anything with a modern browser in it, that is the same job in less space, and the PNGs written here are already run through oxipng.

PNG remains the right answer where the destination is old or unknown: a print shop, a corporate template, an upload form that lists the formats it accepts. It has been readable everywhere for thirty years, which is a real property and the reason this conversion exists at all.

A common expectation, and the one worth correcting before it costs anyone a folder of files: converting to a lossless format does not undo lossy compression. PNG stores what it is given with perfect fidelity, and what it is given is the JPG with its artefacts already baked in — the haloing around edges and the blocking in smooth areas are preserved exactly, at five to ten times the size.

Where it does help is everything that happens next. Editing a JPG and saving it again compresses it a second time; doing the same work in PNG does not. The gain is in the future of the file, not in its past.

Convert when the picture is about to be edited, when something downstream demands PNG, or when it is going into a design tool that will re-save it repeatedly. In each case the format change buys you no further generational loss.

Leave it alone when the file is simply being sent or displayed. A JPG that looks fine will look identical as a PNG and take several times the space, which slows a page down and fills an inbox for no benefit anyone can see.