UntouchedShort answer
Both settings keep your full-resolution originals in iCloud. Optimize iPhone Storage (the default) frees massive storage by keeping smaller preview versions locally and downloading originals on demand, but causes long videos to buffer or fail offline. Download and Keep Originals keeps every file locally for instant offline playback, but requires enough storage to hold your entire library.
When your iPhone lacks space for the entire library but you cannot afford videos buffering, the most effective solution to get the best of both worlds is keeping chosen originals outside the Photos library container—either manually exporting them to the Files app, or preserving them with verified integrity and instant gallery playback using Untouched. The rest of your library stays optimized in iCloud.
Side by side
| Optimize iPhone Storage | Download and Keep Originals | |
|---|---|---|
| Originals in iCloud | Yes | Yes |
| On your iPhone | Space-saving versions, with originals when there’s room | Every original |
| Space used on iPhone | Much less than your library | About the size of your library |
| Opening an older photo or video | May show a smaller version first, then download | Opens at full resolution immediately |
| Offline | Older items may look soft | Everything at full resolution |
| Default? | Yes, when you turn on iCloud Photos | No |
Where to change it
- Open Settings and tap your name.
- Tap iCloud, then Photos.
- In iOS 27, tap iPhone Storage. In earlier versions the two options are on the Photos screen.
- Choose Optimize iPhone Storage or Download and Keep Originals.
Before switching to Download and Keep Originals, check that you have room: Settings › General › iPhone Storage shows free space, and Settings › [your name] › iCloud › Storage shows how much your photo library takes up.
Which should you use?
- You have plenty of free space: Download and Keep Originals. Simplest, and everything is full resolution offline.
- Your library is bigger than your free space: Optimize iPhone Storage. It’s why the setting exists. Example: a 256 GB iPhone full with a 150 GB library can drop to around 5 GB of photos on the device, well over 100 GB freed. Switching back would need all of that room again.
- Optimize, but a few videos must always play instantly (a newborn’s first steps, a wedding, the last video of someone you miss): neither setting does that on its own, because there’s no per-item choice. Long videos are where Optimize hurts most, since they have to download before they play. Keep copies of those outside the Photos library. How to do that.
Common questions
Does Optimize iPhone Storage lower the quality of my photos in iCloud?
No. Apple states that iCloud Photos stores your originals in their original formats at full resolution. Only the versions kept on the iPhone are smaller.
If I switch to Download and Keep Originals, what happens?
Your iPhone starts downloading the originals of items that only had smaller versions on the device. That uses as much space as those originals take, so make sure you have room first.
Can I choose which photos get optimized?
No. The setting applies to your whole library. To guarantee particular originals stay on the device, keep a copy outside the Photos library.
Sources
- Manage your photo and video storage, Apple Support
- Back up and sync your photos and videos with iCloud, iPhone User Guide (iOS 27)
- Transfer photos and videos from your iPhone or iPad to your Mac or PC, Apple Support