Windows cannot open most .heic photos out of the box because HEIC uses the patent-encumbered HEVC video codec, and Microsoft does not ship the required decoder with every copy of Windows. You have two ways out: install Microsoft's HEIF and HEVC extensions, or simply convert the files to a universal format with HEIC to JPG, which decodes the photo on your own PC and never uploads it.
Why Windows chokes on HEIC
HEIC (High Efficiency Image Container) is what iPhones save by default. It stores a photo at roughly half the size of an equivalent JPG, which is excellent on the phone and awkward everywhere else. The image data inside is compressed with HEVC, also known as H.265 — a codec covered by a thicket of patents and licensing pools. Shipping an HEVC decoder in every Windows install would mean paying for every one of those licences, so Microsoft splits it out into a separate extension instead.
The result is the error people actually hit: you copy photos off an iPhone, double-click one, and Windows Photos tells you the file cannot be displayed, or File Explorer shows a blank grey thumbnail where the picture should be. The file is not corrupt. Windows simply cannot read it.
Option 1: install the HEIF extension
In the Microsoft Store, the "HEIF Image Extensions" package is free and adds container support. The catch is that it depends on "HEVC Video Extensions" for the actual decoding, and that one has historically been a paid listing, though some PCs get a free device-manufacturer version pre-installed. Once both are present, Photos and Explorer thumbnails start working.
This is a reasonable fix if the PC is yours and you handle iPhone photos constantly. It is a poor fix if you are on a work or campus machine where you cannot install Store apps, if you only have a handful of photos to deal with, or if the person you are sending the photos to will hit exactly the same wall on their end. Installing an extension fixes your PC; it does not fix the file.
Option 2: convert the file to JPG
Converting solves the problem permanently and for everyone downstream. JPG opens on every version of Windows, every browser, every upload form, and every photo printing kiosk, with no extensions and no explanations. Open HEIC to JPG, drop in one or many .heic or .heif files, and download the JPGs. If you need transparency or a lossless result — for editing rather than sharing — use HEIC to PNG instead.
Why the browser route matters here
Almost every HEIC converter you find in search results uploads your photos to a server to decode them. These are personal photos: family, children, holidays, documents you photographed because it was faster than scanning. File Transmute decodes the HEIC with a WebAssembly image engine running inside your browser tab, on your own CPU, so the photo never leaves your PC. It is free, there is no sign-up, there is no daily cap on how many you can convert, and it works with your network connection off.
- No upload, so no copy of your photos on someone else's server.
- No waiting for a slow upload, which matters when you have 200 photos from a trip.
- Batch conversion, so you can select a whole folder's worth at once.
- Works on any Windows PC — locked-down work laptops included, since there is nothing to install.
Honest limitations
JPG is a lossy format, and so is HEIC, so converting between them re-encodes the picture once. On a normal photo this is invisible, but it is not free: do not convert, edit, and reconvert the same image repeatedly. JPG also has no transparency and does not carry Apple's Live Photo motion data, depth maps, or HDR gain maps — the still frame survives, the extras do not. And a JPG is typically about twice the size of the HEIC it came from, which is the price of universal compatibility.
Stop the problem at source
On the iPhone, open Settings, then Camera, then Formats, and choose "Most Compatible." New photos will be captured as JPG and Windows will open them without complaint. Everything already sitting in your camera roll stays HEIC, so convert that backlog once and be done. If you are gathering the converted photos for a report or a claim, you can then bundle them into a single document with Images to PDF, or pull the text out of a photographed document with Image to Text — both, like the converter, run entirely on your own machine.