There’s little more frustrating than running out of space, which always seems to happen at just the wrong time. Luckily, Apple makes it easy to check any time, before it becomes a problem. On the Mac, choose About This Mac from the Apple menu and click Storage.
On an iPhone or iPad, navigate to Settings > General > iPhone/iPad Storage.
For iCloud, you can look in either System Preferences > Apple ID on the Mac or in Settings > Your Name > iCloud > Manage Storage on an iPhone or iPad.
Once you know how much space is consumed by what, you can more easily clear unnecessary data.