See what is actually using it
Settings → your name → iCloud, then Manage Account Storage. A bar chart shows the breakdown, and it is nearly always the same two things at the top: Photos, and device backups.
Tap either for detail. Backups lists every device backing up to this account, including phones you no longer own — which is frequently the easiest gigabytes you will ever reclaim.
Delete backups for devices you no longer have
Manage Account Storage → Backups shows each device with its size and last backup date. A backup for an iPad you sold two years ago is pure waste, and deleting it is safe.
Be careful with the device you are holding. Deleting its backup also turns iCloud Backup off for it, leaving you without one until you turn it back on and let it run.
Photos is usually the largest single item
If Photos is filling iCloud, the honest options are narrow. Deleting photos frees the space but removes them from every device, since the library is synced. Optimise iPhone Storage reduces what they use on the phone but not in iCloud.
The realistic choices are to move photos out to a computer or another service and then delete them, or to pay for a larger plan. Our photos guide explains why there is no third option.
Trim what does not need to be there
Under Manage Account Storage, apps that store data in iCloud are listed individually and many can be turned off without consequence — an app caching gigabytes of documents you never open, for example.
Mail is worth checking if you use an iCloud address: large attachments in old mail count against the same allowance. And iCloud Drive holds anything you or an app ever saved there.
Upgrading, and sharing the plan
Settings → your name → iCloud → Manage Account Storage → Change Storage Plan shows the current tiers. The 5 GB free tier has not changed in many years and is not enough to back up a modern iPhone, which is the root of most of these problems.
Paid plans can be shared with a Family Sharing group at no extra cost, so one subscription can cover a household. If several people in your family are each paying for storage, consolidating is usually cheaper.
When your iPhone stops backing up
The most common symptom of a full iCloud is backups silently failing. Settings → your name → iCloud → iCloud Backup shows the last successful backup date — if it is weeks old, this is why.
A backup to a computer costs nothing and is more complete than an iCloud backup. Our backup guide covers the difference between the two and when each one matters.
Frequently Asked Questions
What is using my iCloud storage?
Almost always Photos and device backups. Settings → your name → iCloud → Manage Account Storage shows the breakdown.
Is it safe to delete an old iCloud backup?
Yes, for devices you no longer own. Deleting the current device's backup also disables iCloud Backup for it until you turn it back on.
Does iCloud storage affect iPhone storage?
No. They are separate and run out independently. A full iCloud does not fill your phone.
Can I share an iCloud plan with my family?
Yes. Paid plans can be shared with a Family Sharing group at no extra cost.