Your iPhone saves photos as HEIC (High Efficiency Image Container) because it stores the same quality as JPG in roughly half the space. Apple made it the default in iOS 11. The problem: Windows PCs, older software, and many upload forms don't accept HEIC - which is why the fix is either converting the photos you need to share, or telling the camera to shoot JPG.
What HEIC actually is
HEIC is a container for images compressed with HEVC - the same codec behind 4K video. It's genuinely better compression than the 1992-era JPG standard: about half the file size at equivalent quality, plus support for live photos, depth maps, and burst sequences in one file. Apple adopted it as the camera default in iOS 11 (2017) to halve how much of your storage photos consume.
The catch is licensing and inertia. HEVC decoding requires patent licenses, so Windows shipped without it (the codec is a paid add-on), and thousands of websites, printers, and older apps were written when 'image' meant JPG or PNG.
When to convert vs when to change settings
If you occasionally hit a website or recipient that rejects HEIC, convert just those photos and keep HEIC as your camera format - the storage savings on your phone are worth it. Converting in the browser takes seconds and doesn't upload your photos anywhere.
If HEIC causes you friction weekly - you're constantly emailing photos to Windows users or uploading to picky forms - change the camera setting instead: Settings → Camera → Formats → Most Compatible. New photos then save as JPG directly. Existing HEIC photos stay HEIC; convert those as needed.
Which format to convert to
JPG is the right choice for sharing: it opens everywhere, and at high quality settings the difference from the original is invisible. PNG is the right choice when you'll edit the image afterwards - it's lossless, at the cost of much larger files. WebP sits between the two and is excellent for web publishing, but shares a little of HEIC's compatibility problem with older software.
One practical note: converting in a browser canvas strips EXIF metadata - GPS location, capture time, device info. For photos you're about to share publicly, that's usually a feature, not a bug.
Tools for this
Frequently asked questions
How do I stop my iPhone from taking HEIC photos?
Go to Settings → Camera → Formats and select "Most Compatible." New photos will save as JPG instead of HEIC. Photos already taken stay HEIC - convert those individually when you need to share them.
Does converting HEIC to JPG lose quality?
Slightly, because JPG is also a lossy format - but at the 92% quality level typical converters use, the difference is invisible for sharing, printing, and web use. Keep the original HEIC if you want a pristine copy.
Why can't Windows open HEIC files?
Decoding HEIC requires HEVC codec licenses that Windows doesn't include by default - Microsoft sells the extension separately. Converting the photo to JPG sidesteps the licensing problem entirely.