The short version
HEIC is a photo file format. It's the default that iPhones use to save photos since iOS 11 (2017). Files are about half the size of JPG at the same quality — great for iPhone storage, frustrating everywhere else, because most non-Apple software doesn't read HEIC out of the box.
If you got here because Windows or some upload form rejected your HEIC, the practical answer is: convert it to JPG. The converter above runs in your browser, no upload, free for single files.
The longer version: what HEIC actually is
HEIC stands for High Efficiency Image Container. It's a variant of HEIF (High Efficiency Image File Format), a 2015 ISO standard. HEIF is the container — the file structure that holds image data, metadata, and optionally multiple frames or depth maps. HEIC specifies that the image data inside is compressed with HEVC, the same codec that powers 4K video streaming.
HEVC compression looks at neighbouring pixels and reuses information — conceptually the same idea as JPG's discrete cosine transform but much more sophisticated, with larger block sizes and more prediction modes. The result is files roughly 40–60% smaller than JPG at the same visual quality.
Why Apple chose HEIC for iPhone
Two reasons. First, storage: a 64 GB iPhone holds roughly twice as many photos in HEIC as it would in JPG. For a device sold in 64/128/256 GB tiers, the marketing math is obvious. Second, dynamic range: HEIC supports 10-bit colour and HDR metadata, where JPG is locked at 8-bit. iPhones since 2017 capture wider tonal ranges than JPG can represent.
Apple has steadily pushed adoption. Cameras default to HEIC on every iPhone since the iPhone 7 unless you opt out. iCloud Photos store the originals as HEIC. macOS Photos and Preview handle them transparently. Within Apple's ecosystem, you may never notice the format change.
Why HEIC breaks outside the Apple ecosystem
HEVC, the codec inside HEIC, is patent-encumbered. Decoding it royalty-free requires a licence from the MPEG LA patent pool. This is why:
- Windows ships without HEIC support. The HEVC Video Extensions cost $0.99 in the Microsoft Store, and even then only Microsoft's own apps benefit.
- Most web browsers don't render HEIC inline. Chrome and Firefox don't; Safari does (because Apple).
- Older photo editors (Photoshop CS6, Affinity Photo 1.x, GIMP) don't read HEIC without separate plugins.
- Web upload forms — job portals, government applications, school admission systems — typically reject HEIC at the file picker stage because they can't process it server-side.
- Email clients like Outlook strip or compress HEIC inconsistently.
HEIC vs JPG: when each wins
| Scenario | Keep HEIC | Convert to JPG |
|---|---|---|
| Storing on iPhone | ✅ | — |
| Sharing with non-iPhone users | — | ✅ |
| Uploading to MLS / job portal / government form | — | ✅ |
| Opening on Windows / Linux PC | — | ✅ |
| Editing in older Photoshop / GIMP | — | ✅ |
| Embedding in a website | — | ✅ (or WebP) |
| Archival in iCloud Photos | ✅ | — |
Quick reference: extensions you might see
.heic— standard iPhone single image.heif— same container, sometimes used by Android / cameras.heics— HEIF sequence (think: Live Photo or burst).heifs— alternative HEIF sequence extension.avif— same container family, AV1-compressed instead of HEVC; used on the web
LocalJPG converts all of these to JPG using the same browser-side workflow.
Related: HEIC to JPG converter · HEIC to JPG on Windows 10 · HEIC to JPG on Windows 11 · Why iPhone photos don't open on Windows · HEIC to JPG without uploading