X Resolution / Y Resolution (DPI)

The intended print density in pixels per Resolution Unit — what everyone calls the DPI. It's a label and does not affect the pixels.

EXIF tag ID: 0x011A / 0x011B
Group: Image
Example: 72 · 240 · 300
Editable in EXIF Viewer: Yes

What iPhone writes

72.

What dedicated cameras write

Often 300 (Canon, Nikon) or 350 (Sony). Irrelevant until you print.

How to view X Resolution / Y Resolution (DPI) on iPhone

Open the photo in Photos, tap Share, then View EXIF (EXIF Viewer’s action extension). The field is listed under “Image”. Tap Edit to change it, or select several photos in the app to change them all at once. Or drop the photo into the free online EXIF viewer.

Related tags

Resolution Unit — Whether X/Y Resolution are per inch or per centimetre.
Image Width (Exif Image Width / Pixel X Dimension) — Width of the image in pixels, as recorded in the EXIF.