How to reduce photo size on iPhone

The HEIC problem comes first

By default, an iPhone saves photos as HEIC rather than JPEG. HEIC files are smaller than JPEG at the same quality, which is why Apple chose it — but support outside Apple devices is patchy.

The practical consequence: Safari can open HEIC, Chrome and Firefox usually cannot. If you open a compressor in Chrome and drag in an iPhone photo, it may fail before compression even starts. This tool detects that case and tells you rather than failing silently.

Option 1: compress in Safari (fastest)

Open this page in Safari on the iPhone itself, choose the photo from your library, set the target size, and save the result to Files. Safari decodes HEIC natively, so nothing needs converting first.

Option 2: stop shooting HEIC altogether

Settings → Camera → Formats → Most Compatible makes the camera save JPEG from then on. It costs a little storage per photo and removes the compatibility problem permanently. Existing HEIC photos are not converted retroactively.

Option 3: use the Mail trick

Emailing a photo to yourself and choosing a smaller size when prompted produces a JPEG, but you have no control over the target size and the result is often still too large for a strict form. It is a fallback, not a solution.

What not to do

Screenshotting the photo and cropping it does shrink the file, but it also captures the screen's colour profile and softens fine detail. For a document or a face, it is worse than a proper re-encode.