For an existing iCloud Photos library, Optimise iPhone Storage lets the iPhone keep smaller versions as needed while originals remain in iCloud. Check syncing and your independent copies before making the change.
This guide is for someone already using iCloud Photos. Turning it on for the first time introduces an upload and account-storage decision that is outside this small task.
What you need
Your iPhone, a working iCloud Photos account with enough capacity and a reliable connection. Keep a checked independent copy of important pictures. If you cannot confirm where the originals are, pause before any photo cleanup.
1. Record the storage problem
Open Settings > General > iPhone Storage and note the available space. Then open Settings > your name > iCloud to check the account’s storage separately.
If the shortage is in iCloud, optimisation does not reduce the size of the cloud collection. Resolve that account issue without treating manual photo deletion as the same task.
Look at the device’s largest categories too. A replaceable download may offer the room you need with less work.
2. Check the library and your copies
Confirm the Apple Account is the one you intend to use. Check Photos’ syncing status and resolve pending or paused uploads first.
From iCloud.com or another connected device, open a recent image, an older favourite and a video. Inspect the actual items, not just a count. If any expected item is missing, keep local material and investigate.
Check your separate recovery copy as well. An export should include the originals, useful edits and information you intended to preserve. There is no need to delete the source to test recovery.
3. Select optimisation
On the iPhone, open Settings > your name > iCloud > Photos. With your existing syncing arrangement in place, select Optimise iPhone Storage.
Do not manually delete pictures to help optimisation along. In an iCloud Photos library, deletion can apply across the synchronised collection.
The phone manages the space-saving process. It may not immediately free the amount you hoped for, and this guide does not promise a fixed saving or completion time.
4. Check the result later
Allow the phone to finish its work, then return to Settings > General > iPhone Storage and compare the same reading.
Open the recent photo, older favourite and video again. Confirm the cloud collection remains accessible. If something is missing, stop further changes and check the account, connection and syncing status.
Full originals may need downloading when you open them. Before a trip, prepare a small local viewing set and test it without an internet connection. Seeing a thumbnail at home does not establish offline access.
Check your result
You should know that optimisation is selected, which account holds the originals and whether your sample items open. Record any remaining storage shortage rather than reaching for Delete.
If the device reading has not changed, that alone does not mean photos were lost or the setting failed. Recheck the operation and Apple’s current guidance. Do not repeatedly toggle syncing or add another cleaner while the cause is unclear.
An independent copy still needs updating as you take new pictures. Optimisation is a way to manage device space, not a replacement for your wider photo-protection routine.
Keep your note brief: date, action, space before and after, sample checked, offline needs outstanding. A useful record helps you avoid repeating the same uncertainty next month.
Next step
Download a small iCloud batch to Windows if you need a separate folder of originals there.
Sources and scope
Researched 9 September 2026: Apple photo-storage options and iCloud download and deletion behaviour. Documented controls with editorial checks; no hands-on optimisation test is claimed.