Convert PNG to JPG

What changes when you convert

Two things change at once, and they are not equally reversible. The file gets smaller, and any transparency is filled in with a solid colour, usually white. The first is easy to undo by re-exporting from the original. The second is not, because the pixels behind the transparent area were never in the file, so JPG invents whatever is under the alpha channel. That is why the background colour setting matters more here than any quality slider.

Choosing the background colour for transparent areas

When transparency is removed, whatever fills it becomes part of the picture and will be visible wherever the original was see-through. White is the default and suits a document or a logo on a light page. A colour matching the surrounding image suits a cutout placed on a coloured background. Black is a frequent accident and produces a harsh outline, so it should be chosen deliberately rather than left as a default.

• White suits documents, receipts, and anything on a light page.
• A colour matching the image suits a cutout that will sit on a matching background.
• Black produces a hard edge and is rarely what people want by accident.
• Check the result at the edges, where the fill colour is most obvious.
• If the transparency is essential, keep the PNG instead of converting.

NoteIf the image will be viewed on a dark background, a white fill will create a visible rectangle. Choose the fill to match where it will be displayed.

When JPG is the right choice and when it is not

JPG is the right output for photographs, for anything going into email, for form uploads that reject PNG, and for anywhere file size matters more than edges. It is the wrong output for a logo, an icon, a screenshot, a diagram, or anything with a flat background, because JPG has no alpha channel and its compression artefacts are worst exactly on the hard edges and flat areas that matter most in those files. Keeping a PNG in those cases costs a few kilobytes and avoids a visible problem.

• Use JPG for photographs, email, and general uploads.
• Keep PNG for logos, icons, screenshots, and diagrams.
• Use WebP or AVIF for the web when the destination accepts them, since both support transparency better than JPG can.
• If the file has transparency and it must be preserved, do not convert to JPG.
• If it has no transparency at all, a straight JPG conversion is usually an improvement.

Quality settings and file size

Because JPG is lossy, the quality setting decides how much detail is discarded. A balanced setting is a good default for a photograph, and the result is usually a fraction of the PNG size. Going higher produces a larger file that may look marginally cleaner when zoomed, which is rarely worth it for a normal image. The useful comparison is not the quality number but the file size at which the result looks the same as the original at its display size.

• Balanced quality suits most photographs displayed at normal size.
• Check the result at 100 percent, where JPG artefacts are visible.
• Look for ringing around sharp edges and banding in skies.
• Keep the original PNG. Re-exporting from it is better than converting a previous JPG.