Convert JPG photos to PNG when you need a lossless format — for editing, layering, or a tool that requires PNG specifically. Note: PNG can't add back detail JPG already compressed away.
or choose a file from your device — processed locally
PNG is lossless and widely required by design tools, some print workflows, and anything that needs to layer or re-edit an image without further quality loss. Converting doesn't undo JPG's original compression — it just stops any further loss from this point on.
PNG files are usually bigger than the JPG you started with, since PNG doesn't use the same lossy compression. If size matters more than losslessness, keep the JPG or try JPG to WebP instead.
PNG suits logos, screenshots, diagrams and images you will edit again, because saving a PNG repeatedly never adds new compression loss. For ordinary photos it usually just makes the file bigger without making it look better, so keep the JPG if you only need to share or upload the picture.