Open the storage settings
On macOS Ventura 13 or later, choose Apple menu → System Settings → General → Storage. On older versions, look under About This Mac → Storage. Menu labels and the available category details vary by version.
Wait while macOS calculates usage. Write down the available space and the largest categories. If you use external drives, make sure you are looking at the disk that is actually reporting a space problem. A drive attached for backups does not add room to the internal startup disk.
Read the categories without treating them as a delete list
Documents can include substantial personal files and project material; Applications points you toward installed software; Photos may represent a library you want to preserve. The biggest category suggests where to investigate, not what to erase automatically.
System Data is a broad classification, not a single folder you can safely empty. It can contain data that does not fit other categories. Two utilities may group or measure storage differently, so a difference in their totals does not by itself prove that either one missed removable files.
For example, if your Documents category is much larger than the others, reviewing old video exports is a more targeted first step than blindly removing files from Library. If a download or installation is still running, wait before comparing before-and-after figures.
Choose one cleanup action you can verify
Start with files you recognize and no longer need. An old disk image, an exported video with a verified backup, or a forgotten download is easier to evaluate than an unfamiliar support folder.
- Inspect Downloads and sort candidates by size.
- Use Finder to locate large files and confirm what each one contains.
- Move keepers to an external drive only after checking that the copy opens.
- Review the Trash before emptying it.
- Reopen Storage and compare the same disk after its figures update.
When a cleaner app is useful
If manual inspection means repeatedly opening the same folders, a scanner can consolidate that review. Storage Cleaner: Disk & Cache groups large files, caches and developer files in authorized locations. It offers free scanning; cleaning requires a purchase.
The app does not turn disk capacity into extra RAM, and it cannot promise to remove every item counted as System Data. Use it to identify candidates, then make the same keep-or-remove decision you would make in Finder.
Once you have enough room for your immediate task, stop and use your Mac normally. A periodic review of downloads and finished projects is easier to maintain than repeatedly trying to make every storage category look empty.