Why your iPhone shoots HEIC
Since iOS 11 arrived in 2017, iPhones have saved photos as HEIC by default. It is Apple's name for images stored in the HEIF container using HEVC compression, the same technology behind modern video. The appeal is simple: a HEIC photo is typically around half the size of an equivalent JPG at similar quality, so your phone fits roughly twice as many photos in the same storage.
The trouble starts the moment those photos leave the Apple ecosystem. Windows cannot open HEIC out of the box because it lacks the HEVC decoder (Microsoft sells one as a paid store extension), and plenty of upload forms, older photo editors, printing services and workplace systems simply reject the format. Converting to JPG gives you a file that has opened everywhere since the 1990s.
How this converter works, and why it is different
Almost every HEIC converter site works the same way: you upload your photos to their server, the server converts them, and you download the results. Your personal photos, complete with any embedded location data, travel across the internet to a machine you know nothing about. This tool takes the opposite approach. The HEIC decoder runs inside your own browser, so your photos never leave your device, nothing is stored anywhere, and closing the tab removes every trace. That matters when the photos are of your family, your documents or your home.
Under the hood, each photo is decoded and re-encoded as a JPG at the quality you set on the slider. Every decoded image is just a grid of pixels, three bytes each for red, green and blue:
Both HEIC and JPG compress that grid enormously; HEIC just does it more efficiently, which is why your JPGs will come out larger than the originals. Conversion is powered by the open source heic2any library, a browser wrapper around libheif.
Choosing a quality setting
The default of 90% is a sensible sweet spot: visually identical to the original for almost all photos, without the bloat of 100%. Nudge it lower if file size matters more than pixel-level fidelity, or higher if the photos are heading to print. Change the slider after converting and the batch converts again at the new setting.
Because everything runs in your browser, each photo takes a moment to decode and re-encode. A handful convert in seconds; a very large batch will be noticeably slower than a native desktop app, and the progress note keeps you posted. For hundreds of photos at a time, converting in a few smaller batches keeps things responsive.
Stopping the problem at the source
If you regularly send photos to Windows users or upload them to fussy websites, you can tell your iPhone to shoot JPG instead: go to Settings, then Camera, then Formats, and choose Most Compatible. The trade-off is that your photos take up roughly twice the space on the phone. A gentler middle ground is Settings, then Photos, where setting Transfer to Mac or PC to Automatic keeps HEIC on the phone but converts photos to JPG whenever you copy them to a computer over a cable. Either way, keep your originals until you are happy with the converted copies.
Frequently asked questions
What is a HEIC file?
HEIC is the photo format iPhones have used by default since iOS 11 in 2017. It stores images with HEVC compression inside a HEIF container, which makes files roughly half the size of an equivalent JPG at similar quality. That is great for phone storage but bad for compatibility, because much of the software world still expects JPG.
Why can't Windows open my HEIC photos?
Windows does not ship with a full HEVC decoder, partly because of patent licensing costs, so HEIC photos often show as blank icons or fail to open. Microsoft sells an extension in its store, but converting to JPG is free and gives you files that open everywhere, on any system, however old.
Are my photos uploaded anywhere?
No. Most HEIC converter sites send your photos to their server, convert them there and send back the result. This one does not. The decoding and conversion run entirely inside your browser, so your photos never leave your device, nothing is stored, and closing the tab removes everything.
Why do large batches take a while?
Because the conversion happens in your browser rather than on a server or in a native app, each photo takes a moment to decode and re-encode. A handful of photos convert in seconds, but a very large batch is slower than a dedicated desktop app would be. The progress note shows exactly where the batch is up to.
Does converting lose quality?
A little, because JPG is a lossy format. At the default 90% quality the difference is invisible for almost all photos. Drag the slider higher for a closer match and a bigger file, or lower for smaller files. Expect the JPGs to be noticeably larger than the HEIC originals either way, since HEIC compresses more efficiently.