Make your iPhone save JPG from now on
On the iPhone, open Settings, then Camera, then Formats, and choose Most Compatible. New photos are then saved as JPG instead of HEIC. Photos you already took stay HEIC, so convert those here. Most Compatible photos take more space on the phone.
Sometimes the iPhone converts for you
When you send photos with AirDrop to a Mac, attach them in Mail, or share them to some apps, iOS often turns them into JPG automatically. The exact result depends on the app and your iOS settings, so if you end up with a .heic file anyway, use this page.
What HEIC is and why it won't open
HEIC (also written HEIF) is the photo format iPhones use by default. It keeps pictures sharp at about half the size of a JPG, but many Windows apps, older Android phones, email clients, print shops and upload forms can't open it.
A JPG opens almost everywhere, so converting is the quickest way to share or upload a photo. PNG also opens everywhere and never loses detail, but the files are much larger.
Private by design
Your photos are converted inside this page. Nothing is uploaded and the page cannot make network requests to other sites. Location, camera model and the date taken are not copied into the new file, so it is safe to share. Photos are turned the right way up, and if a HEIC file holds several pictures (a burst or the still from a Live Photo), the main one is converted.
Questions
Are my photos uploaded anywhere?
No. The conversion runs in your browser and the page blocks network requests to other sites, so your photos never leave your device.
Can I convert many photos at once?
Yes. Add as many as you like. They are converted one after another so your device stays responsive, and you can download each photo or everything as a single zip.
Does the photo keep its location and date?
No. The new file is built from the pixels only, so GPS location and camera details are removed. That is useful for privacy, but it means the date taken is not kept either.
Why does a very large photo take longer or fail?
A 48 megapixel photo needs a lot of memory to decode. If a photo fails, close other tabs or convert it on its own.
Will Most Compatible change my old photos?
No. It only affects photos you take afterwards. Earlier photos stay as HEIC until you convert them.