Drop HEIC photos above, download PNGs. Batches are fine, and every file converts on your own device.
When PNG is the right target: an uploader or workflow that demands PNG specifically, or a photo heading into further editing. PNG is lossless, and nothing degrades on the next ten saves. For everyday sharing, HEIC to JPG gives far smaller files.
Size: HEIC is the most compact of the three formats and PNG is the largest: a 2MB HEIC often becomes a 10MB PNG, because PNG stores every pixel exactly as it stands while HEIC discards what your eye is unlikely to miss. If the size surprises you, JPG at 90% quality looks identical in normal use at a fraction of the bytes.
Why the file exists at all: iPhones have shot HEIC by default since iOS 11. It stores photos in about half the space of JPG, which is good for the phone and useless when software on the other end refuses it. The full picture, including fixes that skip converting entirely, is in the HEIC guide.
Burst photos: a HEIC container can hold several frames, and the primary image is the one that converts.
Each file shows its own progress and sizes, and downloads individually or as a ZIP.