Currently the newest iPhone models, iPhone X, iPhone 8, iPhone 8 Plus, iPhone 7 and iPhone 7 Plus, will shoot photos in HEIF format by default and you have the option to shoot JPEG pictures using new iPhone. Each has its own merits and drawbacks. HEIF may save more storage space whereas JPEG is universally compatible with basically any phones and other devices. The best solution to this problem for now is to capture photos as HEIC for smaller file size but better image quality, and convert iPhone photos to JPG, JPEG, or or other file format like TIFF, PNG when needed.
How to shoot JPEG photos using iPhone?
You need to configure the settings of iOS 11 to let your iPhone 8, iPhone 8 Plus, iPhone X or later to be able to capture photos in JPEG file format rather than HEIF format. Launch the Settings on iPhone, tap Camera >> Formats, then select Most Compatible other than High Efficiency to force your iPhone camera to shoot photos in JPEG format. See below screenshot.
When the Most Compatible setting has been enabled, all photos will be captured and saved as JPEG files on your iPhone. This does not affect existing HEIC photos in your Camera roll. You can find more details about how you can convert HEIC, HEIF photos to JPG files below.
Convert HEIF HEIC to JPG format on computer
You can convert the HEIF images to JPEG on iPhone as we have mentioned at the first paragraph above or transfer iPhone HEIF photos to computer as JPG files with the image transfer compatibility option turned on without the need for an image converter.
If the iPhone photos have already been exported and saved on your computer as HEIC files, you can follow these steps to batch convert HEIC to JPG on computer using a free HEIF conversion utility.
Update Jan 2018: this article was originally published in 2017. In this update, the new method to convert iPhone photo to JPEG, JPG or image file format on iPhone without loading off to computer was added.