HEIC to JPG

HEIC is what an iPhone has saved photos as since iOS 11, and it is genuinely better than JPEG: roughly half the size at the same quality, with support for 10-bit colour, transparency, depth maps and Live Photos.

The problem is not the format, it is the licence. HEIC stores its pixels as an HEVC video frame, and HEVC is covered by patent pools that charge for decoders. Apple pays for one because it also sells the hardware. Google, Mozilla and Microsoft largely do not, so Chrome, Firefox and Edge will not open a HEIC file at all, and neither will most upload forms, most Windows software and most print shops.

That gap is the whole reason this page exists — and it is why "heic to jpg" is searched half a million times a month.

On Safari and on iOS, the operating system already has a licensed HEVC decoder, so the browser opens the file directly and nothing at all is downloaded.

Everywhere else, this page loads libheif — the reference implementation, compiled to WebAssembly. It is a megabyte and a half of code, around 510 KB compressed over the wire, which is the honest price of decoding this format. It is fetched once when you open the page rather than in the middle of a conversion, so after that you can turn your Wi-Fi off and keep going.

That is the trade against an upload-based converter: a one-off download on your side, instead of your photographs on someone else's disk.

A phone does not turn the picture when you turn the phone. It stores the frame the way the sensor saw it and adds an instruction saying which way is up.

There are two places that instruction can live in a HEIC file: as a rotation property in the container, or as an EXIF tag. Converters that read only one of them produce sideways holiday photos, and converters that read both and apply both produce upside-down ones.

This reads both, works out which one the decoder has already obeyed, and applies the other only if it has not. Portrait photos come out portrait.

Expect the JPG to be roughly twice the size of the HEIC for the same picture. That is the compression advantage you are giving up in exchange for a file that opens.

Quality is set to 82 by default, which is where most people stop being able to see the difference. Raising it to 95 makes the file substantially larger for a change you will struggle to spot; lowering it below 70 starts to show around hard edges and text.

If the photo is an HDR one — anything shot on a recent iPhone in good light — the highlights are mapped down to standard dynamic range, because JPEG cannot hold them. The result looks slightly flatter than the original does on the phone. You are told when this happens.

Re-encoding through a canvas keeps the pixels and discards everything else: EXIF, GPS coordinates, camera make and model, lens, shutter speed, the timestamp, any embedded thumbnail, and the colour profile.

For a photo you are about to publish this is a feature. A JPEG straight off a phone can carry the exact coordinates of where it was taken, and stripping that before it goes anywhere public is good practice — the conversion does it as a side effect.

The one piece of metadata that is honoured before being dropped is the orientation flag. Phones store photos in the sensor's native orientation with a tag saying which way is up; ignoring it produces sideways pictures. It is applied to the pixels, so the result is upright without needing the tag.

If you need the EXIF preserved, this is the wrong tool — a converter that re-encodes cannot keep it.