Guide
How to convert HEIC to JPG on your iPhone
You do not need a computer, and you do not need to install anything from the App Store. There are three ways to do this on the phone, and the right one depends on whether this is a one-off or a habit.
1. Do it in the phone's browser (best for a one-off)
Open the HEIC to JPG converter in Safari or Chrome on the iPhone, tap the drop area, and pick the photos from your library. The converted files save straight back to the phone.
Nothing is installed and nothing is uploaded — the conversion runs inside the browser tab, on the phone itself. That is worth saying plainly, because most converters that appear in a phone search do the opposite: they send your photos to a server and hand them back.
2. Use the Shortcuts app (best if you do this often)
Shortcuts is built into iOS, so there is nothing to download. Open it, make a new shortcut, and add the Convert Image action with the format set to JPEG. Turn on Show in Share Sheet and the shortcut appears whenever you share a photo.
After that, converting is: select the photos, tap Share, tap your shortcut. It handles a batch in one go, and it works with no signal.
3. Change the camera setting (best for preventing it)
Open Settings → Camera → Formats and choose Most Compatible. From then on the camera saves JPG instead of HEIC.
Photos you have already taken stay HEIC — this only changes what happens next — so most people set this once and convert the backlog with one of the methods above. You do lose the storage saving, which is what HEIC actually buys you.
One setting worth knowing about
Settings → Photos → Transfer to Mac or PC has an Automatic option. With it on, photos are converted to JPG as they copy across a cable. It does nothing for AirDrop, email, or messaging apps — only for a direct cable transfer — so it is not a substitute for converting.
What not to rely on
iOS sometimes converts a photo to JPG on its way out through Mail or a messaging app, and sometimes it does not. It depends on the app and on how the photo was attached, which is why the same person can send a photo that opens fine one week and a HEIC nobody can read the next. If it matters that the file opens, convert it before you send it.