Disk space analyzer for Mac: maps, lists, and forecasts.

What a disk space analyzer does

An analyzer walks every folder on a disk, adds up the sizes, and draws the result so the biggest things stand out. There are three common pictures:

• Treemap. Every file is a rectangle sized by its space, nested inside its folder's rectangle. It's great for spotting one huge file. GrandPerspective and WizTreeMac draw treemaps, as WinDirStat does on Windows.
• Sunburst. Folders become rings around a center, each slice sized by its space, and you click inward to drill down. DaisyDisk is the best-known one.
• List. Folders sorted largest first. Less striking, but easier to read exact numbers from. OmniDiskSweeper, Finder's Calculate all sizes, and du in Terminal all work this way.

Analyzer, monitor, or forecast?

An analyzer is a snapshot of what's on the disk right now. Most people open one after macOS has already said the disk is almost full.

A monitor watches free space over time, so you see the trend, not just the total. A forecast takes that history and projects it forward: “Full in ~41 days.”

Disk Forecast is a monitor and forecast first. It checks free space every hour and, after 3 days of history, shows a countdown in the menu bar. When you need room, it lists the folders taking the most space and a cleanup list with each item explained. It doesn't draw a treemap or a sunburst. If you want one, use it alongside GrandPerspective or DaisyDisk.

APFS gotchas: why analyzers disagree

Run three analyzers on the same Mac and you can get three totals. APFS, the file system on every modern Mac, is why.

• Clones. When you duplicate a file in Finder, the copy shares the original's blocks until one of them changes. Two 10 GB files can use 10 GB. An analyzer that adds up file sizes counts 20.
• Hard links. One file can live at several paths. pnpm, for one, links packages from its store into each project. Count every path and the file counts several times.
• Purgeable space. Space macOS has marked as reclaimable, like iCloud files it can download again. Finder counts it as available, and df counts it as used.
• Local snapshots. Time Machine's local snapshots keep the blocks of files you've since deleted. They aren't files in any folder, so an analyzer can't show them, but they still take space. tmutil listlocalsnapshots / lists them.

Disk Forecast counts allocated space, what the disk actually spends, and counts shared space once. A hard-linked file counts at its first link. An APFS clone counts in full the first time its clone family appears, and after that only for the bytes it doesn't share. Purgeable space and local snapshots appear in its System Data window, where it runs Apple's tmutil to remove snapshots after you confirm.

Disk space analyzers for Mac, free and paid

“—” means we couldn't confirm it from the vendor's own materials as of October 2026.

Each app has a full comparison: DaisyDisk, GrandPerspective, WizTreeMac and the Windows tools, OmniDiskSweeper, Disk Inventory X, DiskBuddy, and Mole. Or see them all at once in every Mac disk app compared.

Which one to use

• You want to see where the space went, once: GrandPerspective for free, or DaisyDisk for the nicest picture.
• You want to know before it's full: Disk Forecast, in the menu bar all day.
• You want nothing new on your Mac: Storage settings and Finder. How to check Mac storage shows five built-in ways.