Guide
How to find duplicate photos on iPhone
Apple's Photos app can find some duplicates automatically, but it only catches exact copies. Here's what it does, what it misses, and how to find the rest.
Use Apple's built-in Duplicates album
Open the Photos app, tap Collections, tap Utilities, then tap Duplicates. iOS scans your library for photos and videos that are exact copies of each other, such as a photo saved twice or duplicated by an AirDrop or import. Tap Merge on a set, or Select All and Merge, to combine them: Photos keeps the highest-quality version along with the combined captions, keywords, and favorite status, and moves the rest to Recently Deleted. If your library has no exact duplicates, the album simply won't appear, which is expected, not a bug.
Scanning isn't instant. iOS indexes your library in the background, so newly added photos may not show up as duplicates right away. Leaving your iPhone charging for a while tends to speed this along.
Why some duplicates never show up there
"Exact copy" is a narrow definition. Apple's Duplicates album won't group two photos from the same burst, a reshoot of the same moment a few seconds apart, or a screenshot you took twice by accident, because none of those are exact copies of the same file. It also won't touch the screenshots and reshoots cluttering your library at all, since none of those are duplicates of anything by Apple's definition. If your camera roll feels full of near-misses that the Duplicates album never finds, this is why.
Find the rest manually, or use an app built for it
You can scroll through your library and compare near-identical shots by eye, which works for a small library but gets tedious fast once you're past a year or two of photos. The alternative is an app that groups near-identical shots, reshoots, and repeat screenshots together so you can compare them side by side instead of hunting for them yourself.