Optimize iPhone Storage: What It Does and How to Turn It On

Optimize iPhone Storage is an iCloud Photos setting. It keeps the full-resolution version of every photo and video in iCloud, and stores space-saving copies on the iPhone when space is needed. Apple turns it on by default with iCloud Photos.

The setting moves the photo library's weight from the phone to iCloud, so it works only while the library fits in iCloud. It applies to the photos and videos in iCloud Photos. It is one of the first settings to check when iPhone storage is full.

What Optimize iPhone Storage Does to Your Photos

With the setting on, the original of every photo and video is stored in iCloud at full resolution. Apple says space-saving copies are stored on the device "when needed", which ties the switch to how full the phone is.

Because the originals live in iCloud, the full-resolution version of an optimised photo is reached through iCloud rather than read from the phone.

Does Optimize iPhone Storage lower photo quality?

Optimize iPhone Storage lowers photo quality only on the copies kept on the iPhone. The originals in iCloud stay at full resolution. Apple's page on turning off iCloud Photos says optimised photos "are not the original resolution" unless the originals are downloaded.

The two storage choices differ in where the originals sit, and that decides what happens later:

Both columns assume iCloud Photos is on, which is also the first step in turning the setting on.

How to Turn On Optimize iPhone Storage

Apple's steps for iOS 27, from its page on managing photo and video storage, are:

1. Open Settings, tap your name, tap iCloud, then tap Photos.
2. Turn on Sync this iPhone.
3. Tap iPhone Storage. This step is new in iOS 27.
4. Make sure Optimize iPhone Storage is turned on.

On iOS 26 or earlier there is no iPhone Storage step. Apple's iCloud Photos page says to choose Optimize Storage directly. Other guides give other routes, but Apple's own route runs through your name and iCloud.

Turning the setting on changes where the originals live. Whether the phone gains any space depends on iCloud.

When Optimize iPhone Storage Does Not Free Up Space

Does Optimize iPhone Storage delete photos?

Optimize iPhone Storage does not delete photos. It replaces originals on the phone with space-saving copies, while the originals stay in iCloud. The number of photos on the phone stays the same, and so does the library in iCloud.

The setting depends on iCloud having room for the whole library. iCloud comes with 5 GB free, and iCloud+ plans add 50 GB, 200 GB, 2 TB, 6 TB or 12 TB. Prices vary by country.

Once iCloud is full, Apple's iCloud storage page says "new photos and videos won't upload to iCloud Photos". Photos that have not uploaded have no copy in iCloud, so they stay on the phone. That is one reason iPhone storage stays full when you have iCloud.

The setting is also not a backup. iCloud Photos syncs deletions, so a photo deleted on the iPhone is deleted everywhere that uses iCloud Photos. Deleted items stay in Recently Deleted for 30 days, and Apple says they do not count towards iCloud storage.

The same syncing decides what happens if iCloud Photos is switched off while the setting is on.

Turning Off iCloud Photos With Optimize iPhone Storage On

Turning off iCloud Photos on an optimised iPhone leaves the phone with copies unless the originals come back first. Apple's page on turning off iCloud Photos offers two choices: Download Photos & Videos, or Remove from iPhone.

Apple advises downloading the originals and making sure the phone has enough storage for them. Without that download, the optimised photos stay at less than their original resolution. On a phone that needed the setting to make room, the full library may not fit.

Turning iCloud Photos off for the whole account works differently. Apple deletes the photos from iCloud 30 days after you stop using the service, and Undo Delete reverses that before then.

Other Ways to Free Up iPhone Storage

Optimize iPhone Storage changes where photos are stored, not how many there are. The iPhone Storage screen in Settings, General shows which apps use the most space. Apple says offloading an app frees its storage but keeps its documents and data.

Deleting photos is what shrinks the library itself. With iCloud Photos on, a deletion reaches iCloud too, and items in Recently Deleted stop counting towards iCloud storage. Screenshots, burst frames and duplicate photos are common candidates, and the wider set of steps for freeing up space on iPhone starts with them.

Going through a camera roll by hand means deciding photo by photo. Apps built for that decision show one photo at a time and delete only what you confirm. Apps such as Swipe Quick do this on the device: swipe left to delete, swipe right to keep. Deleted photos go to Recently Deleted for 30 days.