I have an iPhone 11 Pro running iOS 26.5.2 with 511.6 GB of 512 GB used. My iCloud plan has 6 TB of space, with about 2.2 TB currently occupied, so there should be more than 3 TB available. iCloud Photos is enabled with Optimize iPhone Storage turned on, and mobile data access is allowed.
For years, my iPhone stayed around 350–400 GB full because older photos and videos were optimized and stored mostly in iCloud. Recently, though, the phone repeatedly fills up. I sometimes get an "iPhone Storage Full" warning while recording video, which stops the recording. Photos may sync successfully and free up space temporarily, but within a week the phone is full again.
I have already removed apps, voice memos, message attachments, and other large files. Most of what remains is my photo and video library, which contains about 123,000 items. I do not want to manually delete everything just to make room. I also occasionally see "Syncing with iCloud paused, not enough storage," even though my iCloud account has plenty of available capacity.
Why isn't iCloud automatically keeping the originals off my iPhone? Is there a way to upload everything directly to iCloud without using so much of the phone's physical storage?
3 Answers
Check the iPhone Storage screen carefully to confirm Photos is actually the main user of the space and that there isn’t a large System Data or recently deleted category consuming the capacity. Do not factory-reset the phone as a first step, especially while syncing is incomplete. If the storage warning continues despite Optimize Storage being enabled and enough iCloud space being available, document the settings and contact Apple Support; a stuck Photos sync or software issue may need to be repaired.
With more than 123,000 photos and videos, even an optimized library still needs some local space for thumbnails, indexes, cached previews, recently used items, and temporary files. If the phone gets critically full, Photos may not have enough working room to complete syncing and optimization, which can create a cycle: the phone needs space to sync, but syncing is what would eventually free space. Try freeing a little more room wherever possible, then keep it connected to power and Wi‑Fi so Photos can complete its work.
The two storage limits are separate. Having free iCloud capacity does not increase the iPhone’s 512 GB, and iCloud Photos has to finish syncing before Optimize iPhone Storage can remove many of the local originals. Connect the phone to reliable Wi‑Fi, plug it into power, and leave it undisturbed for several hours or overnight. Also verify that Optimize iPhone Storage is still selected under Settings > Apps > Photos. It normally should not require a daily manual backup, so if syncing keeps pausing, Apple Support should investigate the account or Photos sync status.
I already have mobile data enabled and Optimize Storage selected. I’ll leave it plugged in on Wi‑Fi for a longer period, but the repeated pauses are what worries me.
Most of the remaining space is photos and videos, and I’ve already removed other large categories. I’ll check System Data and Recently Deleted before considering anything more drastic.