The biggest iCloud storage hogs are usually Photos and videos , Messages attachments , and device backups. iCloud can also fill up with app data, iCloud Drive files, and backups from apps like WhatsApp, which can quietly grow over time.

What usually fills it

  • Photos and videos: High-resolution media and duplicates can eat space fast.
  • Messages attachments: Photos and videos sent in iMessage can stay in iCloud and add up over months or years.
  • Backups: Full iPhone or app backups often take a surprisingly large chunk of storage.
  • iCloud Drive files: Documents, downloads, and synced files can build up without being obvious.
  • App data: Some apps keep caches or media that sync into iCloud.

How to check

Go to Settings > your name > iCloud > Manage Account Storage to see the storage breakdown. On iPhone, Settings > General > iPhone Storage also helps identify large app data, downloaded media, and recommendations for cleanup.

Fast fixes

  1. Delete large photo and video duplicates.
  1. Remove big iMessage attachments.
  1. Review and delete old backups you do not need.
  1. Clear unused files in iCloud Drive.
  1. Turn on Optimize iPhone Storage for Photos if you keep a lot of media.

Example

If a few people have sent you long videos in Messages, those alone can take up gigabytes of iCloud space even though the chats look small on screen. That is one of the most common “hidden” causes of a full iCloud account.

TL;DR: In most cases, iCloud storage is mostly photos/videos, message attachments, and backups.