How to open HEIC files on Windows
Why iPhone photos will not open, the three fixes, and the fastest free way to convert a whole batch to JPG.
Why the photos will not open
Since iOS 11, iPhones save photos as HEIC (High Efficiency Image Container), which stores the same picture in about half the space of a JPG. Windows did not ship a decoder for it. On Windows 10 and many Windows 11 machines, Photos shows a broken thumbnail or asks you to buy an extension, Paint refuses the file, and web forms reject it as an unsupported type.
Fix 1: convert them to JPG in your browser
If what you actually want is to use the photos, attach them or send them, converting is the direct answer. Open the HEIC to JPG converter in Edge, Chrome or Firefox, drop the whole folder of photos, and download them as JPGs or as one zip. The decoder (libheif, the same open-source library Linux desktops use) runs inside the browser tab, so the photos are not uploaded and there is no cap on how many you convert. Choose PNG on the HEIC to PNG page for a lossless copy, or HEIC to PDF for photographed documents.
The conversion drops the location and camera metadata unless you tick "Keep EXIF metadata", which is worth knowing before you upload the results anywhere.
Fix 2: install the Windows HEIF extension
Microsoft sells "HEVC Video Extensions" in the Store for a small fee, and the "HEIF Image Extensions" package is free but usually needs the paid HEVC one to decode photos. Some PC makers preinstall a free "from Device Manufacturer" version; searching the Store for it is worth a try. Once installed, Photos, Explorer thumbnails and Paint open HEIC natively. It does not help with websites that reject the format.
Fix 3: a viewer that decodes HEIC itself
IrfanView and XnView open HEIC with their plugin packs, and can batch-convert. GIMP opens HEIC directly. These are the right choice if you want to edit the photos on the PC rather than convert them.
Stop the iPhone making HEIC files
On the iPhone: Settings, Camera, Formats, choose Most Compatible. New photos are saved as JPG at the cost of roughly twice the storage. Separately, Settings, Photos, scroll to Transfer to Mac or PC, and choose Automatic: the phone converts HEIC to JPG when you copy photos over a cable, without changing what is stored on the phone.
Questions
Is HEIC better than JPG?
For storage, yes: about half the size at the same quality, with support for 16-bit colour and live photos. For compatibility, no. Convert when the file has to open somewhere you do not control.
Does converting HEIC to JPG lose quality?
A little, because JPG is lossy, but at quality 90 or above the difference is invisible. Choose PNG for a lossless copy at a much larger size.
Can I convert hundreds of HEIC files at once?
Yes. The browser converter has no file limit; a few hundred photos take a minute or two on a laptop and download as a single zip.
Why does Windows say the photo needs a codec?
Because the built-in Photos app relies on the HEIF and HEVC extensions to decode the format. Install them, or convert the photos.