What is HEIC, and why won’t it open?
Since iOS 11 in 2017, iPhones save photos as HEIC by default (Apple calls the setting “High Efficiency”). HEIC is Apple’s use of HEIF, the High Efficiency Image File Format standardised by MPEG in 2015, with the picture compressed by the HEVC (H.265) video codec. The result is roughly half the size of a JPG of similar quality, which is why your iPhone can hold twice as many photos.
The catch is compatibility. HEVC is covered by patents, so support outside Apple’s world is patchy:
| Where | Opens HEIC? |
|---|---|
| iPhone, iPad, Mac (Photos, Preview) | Yes |
| Safari 17 and later | Yes |
| Windows 10 and 11 | Only with the HEIF and HEVC extensions from the Microsoft Store |
| Chrome, Edge, Firefox | No |
| Most upload forms, printers and older apps | No |
Converting to JPG, the format everything understands, fixes all of that.
How this converter works
Your photos are decoded with libheif, the open-source HEIF library, compiled to WebAssembly so it runs inside your browser. In Safari, which can read HEIC itself, the browser’s own decoder is used. The decoded pixels are then compressed with MozJPEG, an improved JPEG encoder from Mozilla, at quality 90 by default.
Nothing is uploaded: your photos, which often contain your home, family and location, stay on your device. Several photos are processed in parallel, so a holiday folder of a few hundred pictures converts in one go, and you can download them all as a single ZIP.
iPhone photos are often stored sideways with a rotation instruction. The converter applies it to the pixels, so every JPG comes out the right way up in every app.
A worked example
A typical 12-megapixel iPhone photo (4032 × 3024) is about 1.5–2.5 MB as HEIC. Converted at quality 90 it usually becomes a JPG of a similar size or somewhat larger, because JPG compresses less efficiently, while looking the same. If that is too large for email or a form:
- lower the quality to 80, which typically saves 40% or more, or
- run the JPGs through Compress Image and set a maximum width such as 2000 pixels, or
- for a strict limit like “under 200 KB”, use Compress to KB.
Keeping the date taken and location
Every iPhone photo carries EXIF data: date and time, camera and lens, and usually GPS coordinates. By default the converter removes it, which is the safe choice if you are posting or sending photos to people you do not know.
If you are moving photos into Google Photos, a Windows library or a family archive, tick Keep photo info. The EXIF block is copied into the JPG, with the rotation flag reset because the pixels are already upright. This works for JPG output; PNG files are saved without it.
JPG or PNG?
Choose JPG for photos: it is small and opens everywhere. Choose PNG only if an app specifically asks for it or you will edit the image many times; a converted photo as PNG is typically 5–10 times larger than the JPG.
Avoiding HEIC in the future
- Shoot JPG: on your iPhone go to Settings › Camera › Formats and pick Most Compatible.
- Convert automatically when copying to a PC: Settings › Photos › Transfer to Mac or PC set to Automatic makes the iPhone hand over JPGs when connected by cable.
- On a Mac: open the photos in Preview, select them all, then File › Export Selected Images and choose JPEG.
- On Windows: install the HEIF Image Extensions to view HEIC in Photos, then use Save as to export.
For several photos at once, without installing anything, this page is quicker. Want them in one document? Combine the JPGs with JPG to PDF.