Living with a 256 GB MacBook

The base MacBook Air ships with 256 GB, and macOS plus the apps most people install takes 60 to 90 GB of that before a single document exists. It is workable. It requires deciding once where large things live, instead of rediscovering the problem every quarter.

Start from the real number

df -h /System/Volumes/Data

Avail is what exists without macOS freeing anything first. Storage settings will usually read higher, because it adds purgeable space it could reclaim on demand. On a small disk, judge by df — it is the number an installer or a large copy will run into.

The comfortable floor is around 20 GB free. Below 10 GB, macOS starts struggling — swap has nowhere to go and everything feels slow. That is the number to defend.

The four decisions

Made once, these are most of the problem solved.

1. Photos goes on an external drive, or fully into iCloud.

Photo libraries grow forever and are usually the largest single thing on a personal Mac. Two options, and picking either is fine:

• iCloud with Optimize Mac Storage on. Full-resolution originals live in iCloud; your Mac keeps smaller versions and fetches originals when needed. Costs a subscription. Requires accepting that the local copy is not the real one.
• The library on an external SSD. Quit Photos, copy ~/Pictures/Photos Library.photoslibrary to the drive, hold Option while launching Photos, and choose the copy. Open it and check everything is there before deleting the original. Portable SSDs are fast enough that you will not notice a difference.

2. Downloads gets emptied, not archived.

The single most reliable source of waste on a small disk. Sort it by size occasionally:

ls -lhS ~/Downloads | head -20

Installers and disk images are never needed twice. If a download matters, it belongs in Documents with a real name.

3. Big projects live outside the machine.

Video, virtual machines, Docker images, sample libraries, game installs. Any of these alone can exceed a 256 GB disk. An external SSD is dramatically cheaper per gigabyte than Apple’s upgrade, and it can be unplugged.

Docker in particular deserves a check, because its disk image grows and does not shrink on its own:

du -sh ~/Library/Containers/com.docker.docker/Data/vms/*
docker system prune -a

4. Time Machine excludes what does not need backing up.

System Settings → General → Time Machine → Options, then exclude virtual machines, Docker data and anything you can re-download. This shrinks both your backups and the local snapshots that live on the internal disk.

The habits that keep it there

Check the number monthly. One command. Catching a slide from 60 GB free to 25 GB is easy; discovering it at 3 GB during an export is not.

Empty the Trash when you empty it. Not when you remember.

Watch the two folders that grow silently.

du -sh ~/Library/Containers ~/Library/Application\ Support | sort -h

Messaging and streaming apps cache aggressively. If one has grown to several gigabytes, look for a cache limit in its settings before deleting anything.

Uninstall properly. On a large disk, leftovers are noise. On 256 GB they are real. The full removal process is worth doing here.

What not to bother with

Do not disable swap. You will find advice to. It will not help and it will make things worse.

Do not delete language files or “system junk” packs. The tools that offer this save a few hundred megabytes and occasionally break printing or dictation. Not a trade worth making.

Do not run a cleaner on a schedule. Nothing accumulates fast enough to justify it, and automatic deletion on a disk this tight is how you lose something.

When the answer is more disk

At some point the honest answer is that the machine is too small for the work. Two signs: you are deleting things you actually want every month, or you cannot install a macOS update without a clear-out first.

A 1 TB external SSD costs less than Apple’s 256 GB upgrade did, and it moves with you between machines. Buying one is a better use of an afternoon than a fifth round of clearing caches.

For the routine part of this, CleanSpace’s Space Lens shows the whole disk as a map so you can see what grew since last time, which is the check that matters most on a small drive. But df -h and the du commands above answer the same question, and on a 256 GB machine the discipline matters more than the tool.