When PNG is the format you actually need
Most of the time a JPG is fine. The moments it is not are specific and easy to recognise: an upload form that rejects everything except PNG, a design tool that wants a lossless source, a logo or screenshot where JPG has smeared the sharp edges into a grey haze, or an image you are about to edit and re-save several times over.
That last case is the one people underestimate. Every time a JPG is opened, changed and saved again, the compressor runs afresh and quietly eats a little more detail. Convert to PNG once and that spiral stops: what you save is exactly what you had, however many rounds of edits follow.
What this tool does, and what it cannot do
- It converts the container, not the content. Detail JPG already discarded cannot be brought back by any format.
- It keeps the full resolution. Nothing is downscaled, cropped or re-framed.
- It respects photo orientation. Pictures taken sideways on a phone come out the right way up rather than rotated.
- It expects PNG to be larger. Lossless storage costs space; that is the trade you are making.
If your real goal is a smaller file rather than a lossless one, JPG to WEBP is the better move: WEBP typically lands well under the JPG it came from at the same visible quality. And if the images are pages of a document rather than pictures, JPG to PDF turns the pile into one file that portals will accept.