How to Check Disk Space on macOS: 3 Simple Methods

Introduction / Why This Matters

Understanding how much free disk space remains on your Mac is critically important for stable system performance. When space runs out, macOS begins to slow down, updates stop installing, and applications may crash. This guide will help you quickly and accurately assess the situation using built-in tools, without installing additional software. You'll learn not only the total volume but also be able to find "heavy" large folders that are worth cleaning up.

Requirements / Preparation

• macOS Sonoma, Ventura, or Monterey (instructions are relevant for these and earlier versions).
• Local administrator privileges (access to system folders in Terminal may require sudo).
• Access to a user account.

Method 1: Through the "About This Mac" Menu

This method provides a clear summary of all volumes.

1. Click the Apple logo (🍎) in the top-left corner of the screen.
2. Select the menu item "About This Mac".
3. In the window that opens, go to the "Storage" tab.
4. You will see a colorful chart that breaks down disk usage by category: "Applications", "Documents", "System Data", "macOS", etc. Below the chart, the total disk capacity and free space are indicated.
5. Click the "Manage..." button to get recommendations for freeing up space (automatic removal of old iTunes movies, storage optimization, etc.).

💡 Tip: Hover your cursor over the colored segments of the chart to see the exact size of each category.

Method 2: Use Terminal for Detailed Analysis

Terminal provides the most precise data and allows you to analyze specific directories.

Step 1: Check the total usage of all disk partitions

Open the "Terminal" application (via Launchpad or Finder → Applications → Utilities) and run the command:

df -h

• -h — the "human-readable" flag, outputs sizes in convenient units (GB, MB).
• In the output, look for the line corresponding to your main disk (usually / or /dev/disk1s1s1). The columns Size (total space), Used (used), and Avail (available) will give you an accurate picture.

Step 2: Find the largest folders in the system root

To understand what is "eating" space, analyze the root directories. Be careful: do not delete files if you are unsure of their purpose!

# Show the size of all folders and files in the root partition (/) and sort by descending order
sudo du -x / 2>/dev/null | sort -rn | head -20

• du — calculates disk usage.
• -x — stays within a single filesystem (does not traverse other mounted disks).
• 2>/dev/null — suppresses "Permission denied" errors (for system folders).
• sort -rn — sorts by numeric value in reverse order (from largest to smallest).
• head -20 — shows the top 20 largest objects.

An alternative, more visual option for a specific folder (e.g., ~/Downloads or /Applications):

du -sh ~/Downloads/*
du -sh /Applications/*

• -s — total size for each item in the folder.
• -h — human-readable format.

Step 3: Check the size of user Libraries

Often, huge amounts of space are occupied by caches and application data in the home directory.

# Show the size of main subfolders in Library
du -sh ~/Library/* 2>/dev/null | sort -rh | head -15

Pay attention to the folders Caches, Containers (App Store application data), and Application Support.

⚠️ Important: Analyzing system folders in /Library or /private/var may require sudo. Use sudo du -sh /Library/* with caution.

Method 3: Disk Utility and Third-Party Tools

Built-in "Disk Utility"

1. Open "Applications" → "Utilities" → "Disk Utility".
2. In the left column, select your main disk (e.g., "Macintosh HD").
3. Click the "Info" button (or "Show Info") on the toolbar.
4. A window will appear with detailed information: total capacity, used and free space, and the number of files.

Third-Party Utilities (Recommended)

For visual disk analysis, excellent free and paid programs are available:

• DaisyDisk (paid, but has a trial version): An interactive disk map where each sector is a folder. Very intuitive.
• GrandPerspective (free): Similar visualization in the form of rectangles.
• OmniDiskSweeper (free from OmniGroup): A simple list of folders sorted by size.

These tools allow you to quickly "see" the clutter and make decisions about deletion.

Verifying the Result

After performing any cleanup actions, return to "About This Mac" → "Storage" or run the df -h command in Terminal again. You should see an increase in the Available (free) column or a decrease in Used (used).

Potential Issues

• "Permission denied" in Terminal.
  • Cause: You are trying to get the size of a system folder accessible only to the superuser.
  • Solution: Use sudo before the command (e.g., sudo du -sh /private/var). Enter the administrator password when prompted.
• Discrepancy in numbers between "About This Mac" and Terminal (df).
  • Cause: macOS reserves a portion of space for system needs (e.g., for memory compression, swap files). "About This Mac" may show "available" space accounting for this reserve, while df shows physically free space.
  • Solution: Refer to the data from "About This Mac" to understand how much space is actually available for your files. A difference of 5-10% is normal.
• Cannot delete a file that du shows as large.
  • Cause: The file may be locked by an active application or have extended attributes (e.g., immutable flag).
  • Solution: Close the application that might be using the file. Use lsof | grep /filename to find the process. Removing attributes may require sudo chflags -R nouchg /path.
• Space is not freed after clearing the cache.
  • Cause: Some applications (especially browsers, Adobe) store cache in hidden folders or use filesystem "snapshots" (e.g., in Time Machine).
  • Solution: Ensure you are clearing the correct folders (~/Library/Caches, not ~/Library/Application Support). Also check if the "Optimize Storage" feature is enabled in iCloud settings.

Additional Recommendations

• Regularity: Check disk usage once a month, especially if you have a small SSD (256 GB or less).
• Cleanup Priority: First, look for large files in ~/Downloads, ~/Desktop, ~/Movies, and ~/Music. Then move on to ~/Library/Caches and ~/Library/Application Support.
• Safety: Never delete files from system directories /System, /usr, /bin, or /sbin unless you are following a specific system recovery instruction.
• Backups: Ensure you have a current backup (Time Machine or cloud-based) before mass-deleting unknown files.