How To Find and View the Amount of Free Disk Space on a Drive

From Visual Basic, it is possible to use the Win32 API function GetDiskFreeSpace to find and view the amount of free disk space on a specified drive. The code sample below shows this in practice.

Sample Code

1. Start a new project in Visual Basic. Form1 is created by default.
2. Remove Form1 from the project.
3. Add a BAS module to the project.
4. Add the following code to the Module1 code window:

      Declare Function GetDiskFreeSpace Lib "kernel32" Alias _
         "GetDiskFreeSpaceA"  (ByVal lpRootPathName As String, _
         lpSectorsPerCluster As Long, lpBytesPerSector As Long, _
         lpNumberOfFreeClusters As Long, lpTotalNumberOfClusters As Long) _
   	As Long
   
   
      Public Type DiskInformation
          lpSectorsPerCluster As Long
          lpBytesPerSector As Long
          lpNumberOfFreeClusters As Long
          lpTotalNumberOfClusters As Long
      End Type
   
      Sub main()
          Dim info As DiskInformation
          Dim lAnswer As Long
          Dim lpRootPathName As String
          Dim lpSectorsPerCluster As Long
          Dim lpBytesPerSector As Long
          Dim lpNumberOfFreeClusters As Long
          Dim lpTotalNumberOfClusters As Long
          Dim lBytesPerCluster As Long
          Dim lNumFreeBytes As Double
          Dim sString As String
   
          lpRootPathName = "c:\"
          lAnswer = GetDiskFreeSpace(lpRootPathName, lpSectorsPerCluster, _
          lpBytesPerSector, lpNumberOfFreeClusters, lpTotalNumberOfClusters)
          lBytesPerCluster = lpSectorsPerCluster * lpBytesPerSector
          lNumFreeBytes = lBytesPerCluster * lpNumberOfFreeClusters
          sString = "Number of Free Bytes : " & lNumFreeBytes & vbCr & vbLf
          sString = sString & "Number of Free Kilobytes: " & (lNumFreeBytes _
             / 1024) & "K" & vbCr & vbLf
          sString = sString & "Number of Free Megabytes: " & _
             Format(((lNumFreeBytes / 1024) / 1024), "0.00") & "MB"
   
          MsgBox sString
      End Sub
   
   						

5. Press the F5 key or choose Start from the Run menu to start the program. You will see a message box displaying the free disk space on drive C:.

For help with common system maintenance tasks in Windows Vista, visit the following Microsoft Web page: