A full drive isn't just inconvenient. Below a certain amount of free space, computers slow down noticeably, updates fail, applications refuse to save, and some systems become unstable.
Aim to keep at least 10–15% of your drive free, and more on a small drive. Below that you're in the zone where things start misbehaving in ways that don't obviously look like a storage problem.
Here's the order that recovers the most space fastest.
First: find out where it's actually going
Don't start deleting. Start looking.
Both operating systems have a built-in storage overview — on a Mac, About This Mac → Storage → Manage; on Windows, Settings → System → Storage. These give you a category breakdown and are the right starting point.
For anything more detailed, use a disk analyzer tool, which shows you a visual map of what's consuming space. That's covered in depth in the next article, and it's worth doing before a big clean-up.
The reason to look first is that people are usually wrong about the cause. Someone convinced their photos are the problem often finds it's virtual machines, or caches, or a downloads folder nobody's opened in three years.
The order of operations
Work down this list. Each step is roughly in descending order of space-per-minute-spent.
1. Empty the trash (2 minutes)
Obvious, and routinely skipped. Deleted files sit in the bin consuming full space until it's emptied.
Check other applications' internal bins too — photo applications, email clients, and note apps often maintain their own recently-deleted areas, each holding real data.
2. Downloads folder (5 minutes)
Almost always the single easiest win. Installers, ZIP files you extracted years ago, duplicate PDFs, files you opened once.
Sort by size, take anything large, and be aggressive. Nearly everything in Downloads is either replaceable or already saved somewhere sensible. Then sort by date and delete anything over a year old without looking at it.
3. Old backups and disk images (10 minutes)
Frequently the largest single find.
- Local phone backups on your computer, from devices you no longer own. These are gigabytes each and accumulate silently.
- Old system backups stored locally.
- Disk images and installers for operating systems and applications.
- Virtual machine images, if you have any and don't use them.
Phone backups in particular catch people. Several years of iPhone backups on a Mac can be tens of gigabytes.
4. Caches and temporary files (10 minutes)
Applications cache aggressively — browsers, design tools, video editors, development environments, streaming apps.
Use the built-in storage tools' cleanup options rather than manually deleting from system folders. Deleting the wrong cache can break an application; the built-in tools know which ones are safe.
Browser caches are always safe to clear. So are most application caches, at the cost of things being slightly slower once while they rebuild.
Design and video software deserves specific attention. Editing applications keep render caches and preview files that can run to hundreds of gigabytes. Most have a "clear cache" or "clean database" option in preferences.
5. Applications you don't use (10 minutes)
Sort your applications by size, and by last-used date if your system offers it.
Large applications you haven't opened in a year are the target. Uninstall properly using the system's uninstall process rather than dragging to the bin, so associated support files go too.
Be cautious with anything you're unsure about — some large items are system components.
6. Media: the real consumers (30 minutes)
Once the easy wins are done, this is where the remaining space is.
Video dominates. Old projects, downloaded content, screen recordings, duplicate exports. A single video project can outweigh a decade of documents.
Photo libraries, especially if you have more than one — a common situation after migrating between applications or importing twice.
Music and podcasts downloaded for offline use and never removed.
Games, which are enormous and mostly re-downloadable.
Don't delete these — move them. See below.
7. Duplicates (20 minutes)
The same file in several folders because you copied instead of moved. A photo library imported twice. Documents saved to both the desktop and a project folder.
Duplicate-finding tools exist for exactly this. Run one, review what it finds before confirming, and be careful with anything inside an application's library folder — some applications rely on files that look like duplicates.
Move, don't delete
The reason people stall on this is that everything feels like it might be needed. The way past that isn't ruthlessness, it's relocation.
An external drive for finished projects, old media, archives, and anything you look at once a year. Copy, verify by opening files, then delete from the internal drive.
Cloud storage with on-demand mode, which shows every file while downloading only what you open. Your entire library stays visible and takes almost no local space.
A NAS, if you have one, for household media libraries.
The key discipline: anything you move off the internal drive still needs a backup. An archive on a single external drive is one drive failure away from gone. Two copies, one of them elsewhere.
Cloud sync: the setting most people miss
If you use a cloud storage service, check whether it's set to keep everything downloaded locally.
Switching to on-demand mode — "optimize storage," "files on-demand," "stream files," depending on the service — converts local files back to placeholders. The cloud copy is untouched, files still appear normally, and they download when opened.
This one setting frequently recovers hundreds of gigabytes in minutes, and it's the highest-return single change available to anyone using cloud storage.
Related: check your photo application's setting. "Optimize storage" keeps smaller versions locally with originals in the cloud. Same effect, same caveat — your machine is no longer a complete copy, so make sure something else is.
What not to delete
System folders, unless a built-in tool is doing it. The space savings aren't worth the risk.
Application support and library folders, without knowing what's in them. These hold your settings, plugins, and sometimes your actual data.
Anything in a photo library package. Photo libraries look like folders and are internally structured. Deleting inside them corrupts the library.
Files you don't recognize in your user folder — check before assuming.
Old versions of files you haven't verified you have elsewhere.
The general rule: if you don't know what it is, don't delete it. Find out or leave it.
When the drive is genuinely too small
If you've cleaned thoroughly and you're still short, the problem is capacity rather than clutter.
Options, in order of practicality:
- On-demand cloud sync, if you're not already using it
- An external drive for media and archives — cheapest by far
- A NAS, if several devices need the same material
- Upgrade the internal drive, where the machine allows it — increasingly not possible on modern laptops
- A new machine, if the drive isn't replaceable and the constraint is chronic
For a laptop with a small soldered drive, an external drive plus cloud on-demand is the realistic answer, and it works well.
Preventing the next one
A quarterly ten-minute pass: empty the bin, clear Downloads, check the storage overview.
A scratch folder for temporary work, emptied on a schedule, so transient files never become permanent ones.
Move projects to archive when they finish, rather than when the drive fills.
Keep an eye on the free space number. If it's trending down steadily, that's the signal to act before it's urgent.
Next in this series: What's Actually Taking Up Space? Disk Analyzer Tools Explained