What a HEIC file is, and why it causes trouble
HEIC is the file extension Apple uses for photos stored in HEIF, the High Efficiency Image Format. Since iOS 11, iPhones have saved photos this way by default. The format uses HEVC compression, the same family of technology as modern video, so a photo usually takes less space than a JPG of similar quality.
On an iPhone, iPad or Mac you never notice any of this: the photos simply open. The trouble starts when they leave Apple devices. Many Windows PCs, older Android phones, photo printing services, online forms and website builders cannot open HEIC, or only after extra software has been installed. JPG has the opposite reputation. It is accepted practically everywhere, which makes it the safest format for sharing, printing and uploading.
What changes when a HEIC photo becomes a JPG
The converter decodes the HEIC into pixels and compresses those pixels again as a JPG. Both formats are lossy, so this is a second round of compression: the JPG cannot be better than the HEIC, and it gives up a little detail compared with the original. At the default quality of 90 the difference is usually hard to see in a photo.
Expect the JPG to be larger than the HEIC, often noticeably, because JPG needs more bytes for the same visual quality. A few other things change as well:
- Location and camera data: EXIF metadata, including GPS position, capture date and camera model, is not copied into the JPG. Keep the HEIC if you rely on that information.
- Orientation: the rotation recorded by the phone is applied to the pixels, so the JPG appears upright in every app.
- Colour and HDR: output is in sRGB, and HDR photos are converted to standard dynamic range. Photos captured in the wider Display P3 colour space may look slightly less saturated.
- Live Photos and bursts: only the still image is converted. The short video of a Live Photo is not included, and when a file holds several images, the primary one is used.
Quality and size settings for phone photos
The quality slider runs from 1 to 100 and starts at 90, which suits photos you want to keep or print. For pictures you will send by email or chat, 80 to 85 usually gives a lighter file with little visible difference. Below about 70, artefacts begin to show in skies, skin and other smooth areas.
Dimensions often matter more than quality. iPhone photos are usually far larger than a phone screen or an email needs, so fitting them within, for example, 2,000 pixels in Settings → Size typically shrinks the files considerably. The aspect ratio is always kept, and photos are never enlarged.
The background colour setting only matters for transparent areas, which camera photos do not have.
HEIC vs JPG at a glance
| Feature | HEIC | JPG |
|---|---|---|
| Compression | Lossy, HEVC-based, very efficient | Lossy, older and less efficient |
| Typical size of a photo | Smaller | Usually larger at similar quality |
| Images per file | One or several (for example bursts) | One |
| Colour range | Wide gamut and HDR possible | sRGB, standard dynamic range in this converter's output |
| Opens on | Apple devices; elsewhere not always | Practically everywhere |
| Best for | Storing photos on an iPhone | Sharing, printing, uploading |
If you plan to edit a photo several times, convert HEIC to PNG instead: PNG adds no further compression loss with each save, at the cost of much larger files. And if the photos never leave your Apple devices, there is no need to convert them at all.
Browsers, privacy and an iPhone setting worth knowing
Safari decodes HEIC itself. Chrome, Edge and Firefox cannot, so the first time you add a HEIC file in one of them, Convertisio downloads a built-in decoder of about 2 MB. Only the decoder travels over the network, towards you: your photos are decoded on your device and never uploaded, as the privacy policy explains.
Batches of up to 10 photos are converted one after another and can be downloaded together as a ZIP. On iPhone and iPad, Safari limits canvas size to about 16.7 megapixels, so very large photos are scaled down to fit on those devices, and you are told when that happens.
If you would rather avoid HEIC altogether, open Settings → Camera → Formats on the iPhone and choose Most Compatible. New photos are then saved as JPG, although they take up more storage on the phone. Photos you have already taken stay in HEIC.