What a HEIC file actually is
HEIC is Apple's name for a HEIF image whose pixels are compressed with HEVC (H.265), the same family of codec used for video. The container can hold more than one image plus depth data and thumbnails. At comparable visual quality, HEIC files are roughly half the size of JPEG, which is why iPhones switched to it in iOS 11. The downside is compatibility: many Windows apps, upload forms and older Android versions cannot open HEVC-based images, and some browsers cannot display them at all.
How the conversion works
Because browsers cannot reliably decode HEIC themselves, this tool loads the heic2any library on demand when you press Convert. That library bundles a WebAssembly build of libheif, which decodes the HEVC data to raw pixels in your browser. Those pixels are then encoded as JPG, with a quality slider from 30% to 100% that defaults to 85%, or as PNG. Files are converted one after another, a progress counter shows how many are done, and each result keeps its original file name with a new extension, so IMG_4021.HEIC becomes IMG_4021.jpg.
Worked example
A typical iPhone 12-megapixel photo (4032×3024) is around 1.5 to 3 MB as HEIC. Converted to JPG at 85%, it usually comes out at about 2 to 4 MB, so the file grows even though the pixels are the same. At 100% it can reach 5 to 8 MB. Converted to PNG, expect 15 to 25 MB, because PNG is lossless and cannot exploit photo-style compression. All of these are approximate. For almost everyone, JPG at 85% to 90% is the right choice.
| HEIC | JPG | PNG | |
|---|---|---|---|
| Typical 12 MP photo | 1.5 to 3 MB | 2 to 4 MB | 15 to 25 MB |
| Compression | Lossy (HEVC) | Lossy (DCT) | Lossless |
| Opens everywhere | No | Yes | Yes |
Common mistakes and edge cases
- Live Photos. A Live Photo is a HEIC still plus a separate short MOV file. Only the still image is converted; the motion is not.
- Multi-image HEIC files. If a file holds several images, only the first one is saved.
- Memory on big batches. Decoding happens in browser memory and files are processed one at a time, but dozens of full-size photos can still strain a phone. Convert in groups of 10 to 20.
- Expecting a smaller file. Converting to JPG makes the file larger, not smaller, because HEIC compresses better. If size is the goal afterward, use the Image Compressor or Image Resizer.
- Compressing twice. Converting HEIC to JPG is already one lossy step. Re-saving that JPG at a low quality adds a second round of loss.
Once converted, you can turn the result into a PNG or a WebP for web use. Alternatively, set the iPhone camera to Most Compatible under Settings, Camera, Formats, so new photos are saved as JPG.