Choose PNG over JPG when the photo is going into an editor rather than an email. PNG is lossless, so the conversion introduces no compression of its own, and every subsequent save leaves the pixels exactly as they are. That matters if you are about to retouch, crop, composite or annotate the image.
Where the quality actually stands
Being precise about this, because "lossless" gets over-promised: your HEIC was already compressed lossily by the phone when the shutter fired. PNG preserves the decoded result perfectly, but it cannot recover detail HEVC discarded. What you get is a faithful copy that will not degrade further — a stable master to edit from, not a restored original.
The practical difference from JPG shows up on the third or fourth save. A JPEG re-compressed each time you tweak it visibly deteriorates; a PNG does not change at all.
Be ready for the size
- A 2 MB HEIC commonly becomes a 20–30 MB PNG. That is normal: HEIC is one of the most efficient formats in use and PNG is one of the least efficient for photographs.
- PNG compresses by finding repetition, and photographs — especially ones with sensor noise — contain very little.
- For a whole camera roll this adds up fast. Convert the few images you are actually editing, not everything.
- If you want a smaller lossless-ish file for the web instead, WebP is a much better fit than PNG.
What does not survive
The same things that are lost converting to JPG are lost here too, because they are properties of the HEIC container rather than of the compression: Live Photo video, depth maps used for portrait-mode blur, and Apple’s non-destructive edit history. HDR is mapped down to standard 8-bit colour. EXIF metadata — including the GPS coordinates the phone recorded — is dropped, which is a privacy gain for anything you plan to share.
What does survive is the orientation. Photos shot sideways carry a rotation flag that is applied during decoding, so the PNG is the right way up rather than lying on its side.
When to use JPG instead
If the photograph is going to a person rather than into an editor, convert to JPG. It is a tenth of the size, opens in exactly the same places, and at a sensible quality setting nobody will see the difference. Reserve PNG for images you are about to work on, or for anything where you need the certainty that no further compression is being applied.
Decoding speed
On Safari and iOS the browser reads HEIC itself and conversion begins immediately. On Chrome, Edge and Firefox a 1.4 MB WebAssembly decoder downloads on first use and is cached afterwards, so the first file in a batch is slower than the rest. Everything runs in this tab, on your machine, with no upload at any point.