If you need to find out how much disk space is available on a particular drive, the place to look is in the DriveInfo class.

You can write code like this to tell you what you need to know:

void Main()
{
  // Get all the drives in the system
  var allDrives = DriveInfo.GetDrives();

  foreach (var drive in allDrives)
  {
    // Output name
    Console.WriteLine("Drive {0}", drive.Name);
    // Output drive type
    Console.WriteLine("\tType: {0}", drive.DriveType);
    // Check if drive is ready (to cater for removeable drives)
    if (drive.IsReady)
    {
      // Output label
      Console.WriteLine("\tLabel: {0}", drive.VolumeLabel);
      // Output format
      Console.WriteLine("\tFile System: {0}", drive.DriveFormat);
      // Output free space
      Console.WriteLine("\tAvailable Space: \t\t{0:#,0} bytes", drive.AvailableFreeSpace);
      // Output total size
      Console.WriteLine("\tTotal Size :\t\t\t{0:#,0} bytes ", drive.TotalSize);
    }
  }
}

The property to check here is AvailabeFreeSpace

On my machine, MacBook Pro running macOS 14, it returns the following:

Drive /
    Type: Fixed
    Label: /
    File System: apfs
    Available Space:         76,199,739,392 bytes
    Total Size :            994,662,584,320 bytes 
Drive /dev
    Type: Ram
    Label: /dev
    File System: devfs
    Available Space:         0 bytes
    Total Size :            204,288 bytes 
Drive /System/Volumes/VM
    Type: Fixed
    Label: /System/Volumes/VM
    File System: apfs
    Available Space:         76,199,739,392 bytes
    Total Size :            994,662,584,320 bytes 
Drive /System/Volumes/Preboot
    Type: Fixed
    Label: /System/Volumes/Preboot
    File System: apfs
    Available Space:         76,199,739,392 bytes
    Total Size :            994,662,584,320 bytes 
Drive /System/Volumes/Update
    Type: Fixed
    Label: /System/Volumes/Update
    File System: apfs
    Available Space:         76,199,739,392 bytes
    Total Size :            994,662,584,320 bytes 
Drive /System/Volumes/xarts
    Type: Fixed
    Label: /System/Volumes/xarts
    File System: apfs
    Available Space:         504,692,736 bytes
    Total Size :            524,288,000 bytes 
Drive /System/Volumes/iSCPreboot
    Type: Fixed
    Label: /System/Volumes/iSCPreboot
    File System: apfs
    Available Space:         504,692,736 bytes
    Total Size :            524,288,000 bytes 
Drive /System/Volumes/Hardware
    Type: Fixed
    Label: /System/Volumes/Hardware
    File System: apfs
    Available Space:         504,692,736 bytes
    Total Size :            524,288,000 bytes 
Drive /System/Volumes/Data
    Type: Fixed
    Label: /System/Volumes/Data
    File System: apfs
    Available Space:         76,199,739,392 bytes
    Total Size :            994,662,584,320 bytes 
Drive /System/Volumes/Data/home
    Type: Network
    Label: /System/Volumes/Data/home
    File System: autofs
    Available Space:         0 bytes
    Total Size :            0 bytes 
Drive /private/var/folders/q8/cdslzt2s6p1djnhp_y3ksc280000gn/X/4E6D7E7B-0CA5-51C6-96B7-5184E139C6F7
    Type: Unknown
    Label: /private/var/folders/q8/cdslzt2s6p1djnhp_y3ksc280000gn/X/4E6D7E7B-0CA5-51C6-96B7-5184E139C6F7
    File System: nullfs
    Available Space:         77,716,463,616 bytes
    Total Size :            994,662,584,320 bytes 
Drive /Users/rad/OrbStack
    Type: Network
    Label: /Users/rad/OrbStack
    File System: nfs
    Available Space:         72,555,085,824 bytes
    Total Size :            104,875,864,064 bytes 
Drive /Users/rad/Library/Parallels/Windows Disks/{bb803e4d-ca2b-4ce2-a092-47b37b09cef6}/[C] Windows 11.hidden
    Type: Network
    Label: /Users/rad/Library/Parallels/Windows Disks/{bb803e4d-ca2b-4ce2-a092-47b37b09cef6}/[C] Windows 11.hidden
    File System: smbfs
    Available Space:         75,699,970,048 bytes
    Total Size :            273,435,062,272 bytes

A couple of things of interest:

  • The concept of a Drive goes beyond just physical disks
  • The DriveTypes map to one of the following
  • You should check if the drive is ready before attempting to access it - some drives, such as removable drives might throw exceptions if you try to access them before they are ready.

Note that if you run this code repeatedly your results about free space might change depending on what else the operating system is doing.

TLDR

Use the AvailableFreeSpace property of the DriveInfo object to determine the available free space on your machine.

Happy hacking!