HEIC Explained: Compatibility and Quality

HEIC is the reason a photo that looks fine on an iPhone refuses to open on a work laptop. It is a genuinely better format than JPEG on the technical merits, and it is also the format most likely to be rejected by whatever you need to send it to. This article explains why both things are true and what converting actually costs you. For the walkthrough, see how to convert HEIC to JPG.

Cannot Open File

The file format .HEIC is not supported.

Fix This Now >

What HEIC actually is

Two things are bundled under the name. HEIF, the High Efficiency Image File Format, is a container - a standardised wrapper that can hold one image, a burst of images, a short motion clip, thumbnails, depth maps, and metadata all in one file. HEIC is that container holding images compressed with HEVC, also known as H.265, the video codec.

Using a modern video codec on a still image is what buys the efficiency. HEVC's intra-frame prediction is far more sophisticated than JPEG's 1992-era discrete cosine transform, so a HEIC file typically reaches similar perceived quality at around half the size of the equivalent JPEG. It also stores 10 bits per channel rather than JPEG's 8, which is why HEIC handles smooth gradients like a sunset sky without the banding JPEG shows, and it supports transparency, which JPEG does not.

Apple made it the default capture format with iOS 11 in 2017. If your phone is set to "High Efficiency" in the camera settings, this is what it is producing.

Why compatibility breaks

The problem is not that HEIC is obscure. It is that decoding it requires an HEVC decoder, and HEVC is covered by a large, fragmented set of patent licences. That has real consequences downstream:

Windows needs an extension. Support is not built into a stock install, and part of the required codec package is a paid item in the Microsoft Store.
Software lags. Older versions of Photoshop, Lightroom, Office, and plenty of desktop utilities simply do not recognise the file.
Upload forms reject it. Job applications, insurance claims, government portals, print services, and most content management systems accept JPEG and PNG and nothing else.
The web does not use it. Browser support is inconsistent, so a HEIC file is not a file you can put on a web page.

The practical rule: HEIC is fine as a storage format inside Apple's ecosystem, and unusable as an interchange format anywhere else. Converting is not fixing a broken file, it is translating for an audience that does not speak the language.

The quality tradeoff

Both HEIC and JPEG are lossy, so converting between them re-encodes rather than copies. The decoder reconstructs pixels from the HEIC, and the JPEG encoder then discards information from those pixels according to its own model. That second pass is generation loss, and it is permanent. In practice a good-quality JPEG conversion of a normal photograph is visually indistinguishable at viewing size, but you should expect three specific effects:

Larger files. A JPEG at comparable quality is usually roughly twice the size of the HEIC it came from. Converting a whole camera roll can be a substantial jump in storage.
Banding in smooth gradients. This is the 10-bit to 8-bit reduction. Skies at dusk are where it shows.
Cumulative damage on re-edits. Editing and re-saving a JPEG repeatedly compounds the loss. Convert once, from the original, each time you need a JPEG.

The rule that follows: keep the HEIC originals. Treat the JPEGs as export copies for a specific destination, not as your archive.

What the container loses

A HEIC file can hold more than one picture. Converting flattens it to a single still, so Live Photo motion, burst sequences, and the depth map used for portrait-mode background blur do not survive. HDR gain map information is also discarded, which is why a converted photo can look slightly flatter than the original did on the phone. None of this matters for a receipt or a document scan; it matters a lot for a portrait you might want to re-edit.

JPG or PNG for the output

Our HEIC converter produces JPG, and for photographs that is the right choice - JPEG's compression is designed for continuous-tone imagery and the file stays manageable. Reach for PNG only when the content is not photographic: screenshots, diagrams, images with large flat areas or crisp text, or anything with transparency you need to keep. PNG is lossless, so it introduces no further generation loss, but a PNG of a photograph can be several times larger than the JPEG and gains you nothing visually. If you need the other direction later, the format converter handles JPG, PNG, WebP and BMP in batches.

Or avoid the problem at capture

If you regularly send photos to Windows machines or upload them to web forms, change the setting. On an iPhone, Settings then Camera then Formats, and choose "Most Compatible" instead of "High Efficiency". The camera then writes JPEG directly and there is nothing to convert. You lose the storage savings and the 10-bit depth, which for most people is a fair trade against never hitting the problem again.

Why this one should run on your device

A camera roll is about as personal as files get, and the metadata inside is worse than the pixels: HEIC files from a phone routinely carry GPS coordinates, timestamps, and device identifiers. Uploading a folder of them to an anonymous conversion site hands all of that to a stranger. Our converter decodes HEIC with a JavaScript library running inside your tab and re-encodes on a canvas, so the files never leave your machine. There is no queue, no file-count limit, and no server-side copy to be retained, because there is no server in the path at all.