C# Signature:

[DllImport("kernel32.dll", SetLastError=true, CharSet=CharSet.Auto)]
static extern bool GetDiskFreeSpace(string lpRootPathName,
   out uint lpSectorsPerCluster,
   out uint lpBytesPerSector,
   out uint lpNumberOfFreeClusters,
   out uint lpTotalNumberOfClusters);

VB.Net Signature:

Declare Auto Function GetDiskFreeSpace Lib "kernel32.dll" ( _
     ByVal lpRootPathName As String, _
     ByRef lpSectorsPerCluster As UInt32, _
     ByRef lpBytesPerSector As UInt32, _
     ByRef lpNumberOfFreeClusters As UInt32, _
     ByRef lpTotalNumberOfClusters As UInt32) As Integer

Notes:

In the .Net Framework, this functionality is available in the System.IO.DriveInfo class.

On Windows 95/98 the GetDiskFreeSpace function cannot report volume sizes that are greater than 2 gigabytes (GB). To ensure that your application works with large capacity hard drives, use the GetDiskFreeSpaceEx function. On Windows NT and Windows 2000, GetDiskFreeSpace is not limited to 2GB; it reports the full size of the drive and the full amount of free space. See http://support.microsoft.com/kb/231497 .

Tips & Tricks:

If you are reading information for multiple drives and/or do not need sector cluster information, use the Managed API instead (System.IO.DriveInfo)

Sample Code:

uint SectorsPerCluster;
uint BytesPerSector;
uint NumberOfFreeClusters;
uint TotalNumberOfClusters;

GetDiskFreeSpace("C:\\", out SectorsPerCluster, out BytesPerSector,
   out NumberOfFreeClusters, out TotalNumberOfClusters);

Console.WriteLine("Sectors Per Cluster: {0}", SectorsPerCluster);
Console.WriteLine("Bytes Per Sector: {0}", BytesPerSector);
Console.WriteLine("Number Of Free Clusters: {0}", NumberOfFreeClusters);
Console.WriteLine("Total Number Of Clusters: {0}", TotalNumberOfClusters);    

// SectorsPerCluster * BytesPerSection will give you how many bytes are available per sector
// And by multiplying the result with NumberOfFreeClusters gives you the free space in bytes.
long Bytes = (long)NumberOfFreeClusters * SectorsPerCluster * BytesPerSector;
Console.WriteLine("Total Free Space in bytes: {0} ", Bytes);

decimal KiloBytes = (decimal)Bytes / 1024;
Console.WriteLine("Total Free Space in kilo bytes: {0}", KiloBytes);

decimal MegaBytes = (decimal)KiloBytes / 1024;
Console.WriteLine("Total Free Space in mega bytes: {0}", MegaBytes);

decimal GigaBytes = (decimal)MegaBytes / 1024;
Console.WriteLine("Total Free Space in giga bytes: {0}", GigaBytes);

Console.WriteLine("Please enter any key to exit...");
Console.ReadLine();

Alternative Managed API:

The ManagedWindowsApi project (http://mwinapi.sourceforge.net) provides an ExtendedFileInfo class that can get sector/cluster sizes and counts.

Please edit this page!

Do you have...

• helpful tips or sample code to share for using this API in managed code?
• corrections to the existing content?
• variations of the signature you want to share?
• additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).