HEIC (High Efficiency Image Container) is the format Apple uses by default on iPhones since iOS 11. It produces files roughly half the size of JPEG at equivalent visual quality. This sounds straightforwardly better than JPEG, but HEIC has compatibility limitations that make it the wrong choice in specific situations. Knowing when to use which format avoids both oversized files and sharing headaches.
What HEIC actually is
HEIC is a container format based on the HEIF (High Efficiency Image Format) standard developed by the MPEG group. It uses the HEVC (H.265) video codec for image compression, which is more efficient than the JPEG compression algorithm at equivalent visual quality. A HEIC file is typically 40 to 50 percent smaller than a JPEG of the same image at the same perceived quality.
Beyond smaller file size, HEIC supports features that JPEG does not. These include wider colour gamut for displaying colours that standard JPEG cannot represent, HDR (high dynamic range) data from multiple exposures, depth map data used for portrait mode blur effects, and Live Photo motion data. For images viewed on Apple devices, these features provide tangible quality benefits.
When HEIC causes problems
HEIC is not universally supported outside the Apple ecosystem. Windows requires a paid codec from the Microsoft Store to open HEIC files natively. Many web browsers, email clients, and online services do not accept HEIC uploads. Android devices may not display HEIC files received over messaging. Older software, government portals, and document management systems almost universally lack HEIC support.
When you share a HEIC image with someone using a Windows computer or Android device who does not have the necessary codec or app, they may receive an error message or see a broken image. When you upload a HEIC file to a web form or portal that expects JPEG, the upload will typically fail or be rejected.
iPhone handles some of these situations automatically. When you share a HEIC photo via AirDrop to a Mac, it stays as HEIC. When you share via iMessage to another iPhone, it stays as HEIC. When you email a photo directly from the Photos app, iPhone may automatically convert it to JPEG depending on the recipient's device. When you upload via Safari, iPhone may convert automatically. When you transfer files manually via USB or through third-party apps, the HEIC file is transferred without conversion.
iPhone camera format settings
To change the camera format on iPhone, go to Settings, then Camera, then Formats. Two options appear: High Efficiency (HEIC) and Most Compatible (JPEG). Selecting Most Compatible causes the camera to save all new photos as JPEG from that point forward. Existing photos remain in whatever format they were captured in.
The Most Compatible setting produces JPEG files that are approximately twice the size of the equivalent HEIC. For a phone with 256GB of storage that is primarily used as a personal camera, this difference is noticeable over time. For a phone primarily used for professional or sharing purposes where compatibility is important, the larger file size is a worthwhile trade-off.
A middle approach is to keep High Efficiency as the default and use the sharing conversion feature when distributing photos. When you export or share photos from the Photos app, there is often an option to convert to JPEG for compatibility. This preserves storage efficiency on the device while ensuring shared files are in a universally compatible format.
Converting existing HEIC files to JPEG
Converting a library of HEIC files to JPEG can be done through several approaches. On Mac, dragging HEIC files into Preview and exporting as JPEG is the simplest manual approach. On Windows with the HEIC codec installed, right-clicking and converting through the Photos app works for individual files.
For bulk conversion of large numbers of files, command-line tools or batch conversion applications are more practical. The free ImageMagick command-line tool handles HEIC to JPEG conversion in batch on Mac and Linux. On Windows, various GUI applications provide HEIC batch conversion.
The Convert Image tool handles individual HEIC files for quick conversion without installing software.
File size comparison in practice
A typical iPhone 15 photo in HEIC format runs between 3MB and 8MB depending on scene complexity. The same photo in JPEG at equivalent quality would be between 5MB and 15MB. For a camera roll of 10,000 photos, this difference represents 20GB to 70GB of storage, which is significant on any phone.
For sharing and uploading purposes, converting to JPEG at a reduced quality setting (70 to 80 percent) while also resizing to a web-appropriate width produces files typically between 100KB and 500KB per photo, which is appropriate for email, messaging, and most portal uploads regardless of the original format.
HEIC and professional photography workflows
Professional photographers using iPhone for shooting who then process images in a desktop raw converter should be aware that some applications do not support HEIC. Adobe Lightroom and Capture One both support HEIC import, but older versions may not. If your editing workflow involves software that does not support HEIC, shooting in Most Compatible (JPEG) mode or using the Camera app's RAW + JPEG option (if available on your model) is more practical than converting after the fact.