how can i keep photos in icloud if i delete them on my phone?

To put it in other words - if you want to keep your photos in iCloud but delete old photos from your iPhone, do not enable iCloud Photos on the iPhone. Only if the Photos.app on your iPhone is not syncing with iCloud Photos, the photos you delete on your iPhone will remain in iCloud. Disabling iCloud Photos on your iPhone is the only way to have a different set of photos on your iPhone than in iCloud and on your other device. But it is a high price to pay, as you can no longer access the iCloud photos on your iPhone and iCloud can no longer sync new photos from the iPhone to other devices.

If your iPhone is too small to hold all photos, you have two options, depending on what you want and depending on your access to the internet and data plan:

1. Optimize iPhone Storage: Most users here are recommending "Optimize Storage", if you want to have more photos in iCloud than will fit on the device. This is fine, if you have a very fast internet and always available, where ever you want to use the photos. This would not do for me, because I am finding myself frequently without a decent internet, when I am travelling - on a train or a long distant flight, or hiking trip, or a very poor hotel Wi-Fi. It is very embarrassing, if you want to show a picture to someone and are only seeing blank thumbnails or a spinning beach ball. And it is much more work to make a backup of your photos, if "Optimize Storage" is enabled.
2. Keeping the iCloud Photos Library small: I prefer to archive the majority of my pictures locally on external volumes and to use iCloud Photos only for keeping the photos on my devices in sync, no optimise storage. This requires to keep my iCloud Photos library small enough to fit onto the device with the smallest storage. My iCloud Photos Library is just holding my most important photos, the photos I want to be able on all devices, plus the new photos I am still working on with adjustments and tagging and weeding out bad shots. This has two advantages: My most important photos are saved in iCloud, offsite in addition to my Time Machine backups on the Macs, and I can work with them even offline, without an internet connection. Photos is much faster and responsive with a small library and without "Optimize Storage". I can use all photos immediately in the Media browser. The background processes in Photos to scan the library after a system update are much faster, searches are faster.

Decide for yourself - go for "Optimize Storage", if you are sure you will always have a very fast and reliable and affordable internet connection, or go for a smaller iCloud Photos Library and keep it small enough to fit onto your device without "optimise" and use iCloud Photos only for syncing and off-site storage, but not to save storage on your devices.

althea8690 wrote:

how can i keep photos in icloud if i delete them on my phone?

Do be cautious, here.

If enabled, iCloud Photos is a synchronization service, which means that deleting photos locally will delete them everywhere, across all devices logged into the same Apple ID, including photos stored in iCloud.

if you do have iCloud Photos enabled, then iCloud will manage and cache photos locally, depending on how much free space is available on the iPhone.

But again, if you delete a photo stored in iCloud Photos, it will be deleted everywhere.

Here are some details:

Manage your photo and video storage - Apple Support

Delete photos on your iPhone, iPad, and iPod touch - Apple Support

althea8690 Said:

"so, should you keep all photos in the cloud rather than on your phone to prevent accidental deletion?"

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Export to an External Drive:

No. I'd say back them up to an external drive. Ge here: How to download photos and videos from iCloud.com - Apple Support

They'll be created as a ZIP (compressed) file. Then, move the ZIP file to an external drive.

althea8690 Said:

"how can i keep photos in icloud if i delete them on my phone?"

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iPhone Photo Deletion:

All is fine. As long as they are in iCloud, they will remain in iCloud, deleted from your iPhone or not.

althea8690 Said:

"how can i keep photos in icloud if i delete them on my phone?: Are you certain about that? Just heard on the news that if you delete from your iphone, it deletes from icloud. This was news to me."

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Are these Downloaded?:

When detecting from the Photos app, then they would be deleted from iCloud, if they are not downloaded. So, only the downloads would be deleted from your iPhone. But, if not downloaded, then you're accessing them in iCloud.

althea8690 wrote:

Do you know what to do to prevent this?

I am not sure what you’re trying to do, past (not) deleting photos. There are some possibilities here, including too little iPhone internal storage, and sharing an Apple ID, among other possibilities. Some background here might help.

If you have iCloud Photos enabled, deleting the photo deletes it everywhere. This is the expected and intended behavior. There is no means to alter this behavior, and to continue using iCloud Photos.

iCloud Photos manages the photos stored locally, and will relinquish that storage as the iPhone storage gets more constrained.

You need to nothing for that, as iPhone and iCloud will manage the local cache.

If you want to know more about this topic, please tap or click on the blue-text link previously referenced. That is a link to an Apple article on managing your photos and videos and related storage.

If you are on an iPhone with insufficient internal storage, you will never not be managing storage.

If you are sharing an Apple ID with others, that tends to cause issues. There are ways to share photos without allowing others to delete your photos, such as iCloud with Family Sharing enabled, and shared albums. Sharing an Apple ID tends to get tangled.

See the article Get help with iCloud Photos - Apple Support

You are welcome.

You're welcome 😊