Why Your iPhone Photos Won't Open Anywhere Except Your iPhone

The short version: modern iPhones save photos as HEIC (High Efficiency Image Container) by default — a format that compresses noticeably better than JPG at the same visual quality, which is exactly why Apple switched to it. The tradeoff is that HEIC support outside Apple's own software is inconsistent, so plenty of websites, older apps, and non-Apple devices simply can't open it.

Why Apple picked a format almost nothing else supports

HEIC is built on more modern compression technology than JPG, which is decades old at this point. For the same visual quality, a HEIC file is routinely 40-50% smaller than the equivalent JPG — a genuinely meaningful difference when you're storing thousands of photos on a phone with finite storage, or backing them up over a metered connection. From Apple's side, the tradeoff made sense: better compression, on devices Apple controls completely. The catch is that "controls completely" doesn't extend to the website you're trying to upload a photo to, or your friend's five-year-old Android phone.

Why this shows up as a surprise so often

Most people never notice HEIC exists, because iOS quietly converts photos to JPG automatically in a lot of common situations — texting a photo via iMessage to a non-Apple number, for instance, or exporting through certain apps. The format only becomes visible when you hit one of the paths that doesn't do that conversion: AirDropping the raw file to a computer, plugging your phone in and copying photos directly, or uploading through a website form that expects JPG or PNG and gets neither.

What converting actually does

Converting HEIC to JPG (or PNG, or WebP) decodes the HEIC image data and re-encodes it in the target format — a real re-encode, not a rename, since the two formats compress images in fundamentally different ways. The image itself doesn't change in any way you'd notice; what changes is the container it's stored in, and by extension, what can open it.

How FormatDog's converters avoid uploading your photos to do this

FormatDog's HEIC to JPG tool and the broader Image Format Converter (which also handles PNG, WebP, BMP, and GIF) decode and re-encode images using your browser's own image-processing capabilities and JavaScript running locally — both work on multiple photos at once, entirely on your device. A camera roll full of personal photos never has to leave your phone or laptop just to become a format a website will actually accept.

You don't have to take that on faith

Open your browser's developer tools (F12, or right-click and choose "Inspect"), click the Network tab, then convert a batch of photos and watch what happens. If your images are being uploaded to convert them, you'll see outgoing requests carrying that data appear as each one processes. If the converted files download with nothing showing up there, the conversion happened locally, on your device.

The honest caveat

Converting from HEIC to JPG is technically a lossy re-encode of an already-compressed image, which means a very small amount of additional quality loss compared to the original — in practice, not something you'd notice at normal viewing sizes, but worth knowing if you're archiving photos for the long term and want to keep the original HEIC as a backup alongside the more compatible copy.