FAQ & Knowledge Base

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The last access date of a file is maintained by Windows. Since Windows Vista/Server 2008, Microsoft disabled the automatic update for the "Last access" date by default to improve system performance on NTFS formatteddrives. Because of this, the date won't be updated anymore if a file content is changed for example. That is also the reason why the last access date isn't a good indicator anymore for recent usage of a file.

For more information, see the MSDN homepage.

TreeSize v9.1 is compatible with:

  • Windows 11
  • Windows 10, version 1607 or above
  • Windows 8.1
  • Windows Server 2022
  • Windows Server 2019
  • Windows Server 2016
  • Windows Server 2012 R2
  • Windows Server 2012

We offer versions for older Windows versions and for 32Bit operating systems that can be downloaded in the customer area:

  • TreeSize v8.1.4 for Windows 7, Server 2008 R2, and 32bit/x86 systems
  • TreeSize v7.1.5 for Windows Vista and Server 2008
  • TreeSize v6.3.7 for Windows XP and Server 2003

If you need a different specific version, please contact us directly by using our contact form.

For these outdated versions a trial download is unfortunately not available.

For V8 you need a new license key, you will receive this key after a login in our customer area.

The easiest way to install the update is to use the integrated update function: Click the "Check for Updates" button in the "Help" ribbon bar.

The Windows Explorer and the TreeSize drive list do show the space that is physically allocated on the drive while TreeSize shows the space that is occupied by all files under a certain path. Please make sure that you have the view option "Allocated Space" activated when you are interested in the physically allocated space.

Another possibility is that not all parts of the drive could be scanned due to access restrictions. Therefore it is highly recommended to run TreeSize as administrator. If you want to get notified if a folder cannot be scanned, please open the options dialog (File > Options) and enable "Show error messages during scan" under the option page "Scan > General". Turning on the Option "Track advanced file system features" in the Options dialog may result in more accurate results, because it tracks e.g. hardlinks, but slows down scans. If a drive letter points to a sub-folder of a network drive, the allocated space (correctly) reported by TreeSize may also be much smaller than the physically allocated space on this drive reported by the Windows Explorer because possibly the whole drive is not accessible through the network.

Beyond the space that is needed for storing the files itself, additional space is used for storing management data like the File Allocation Table of the file system or the boot sector. It is not possible to free this space with TreeSize or any other tool. This is usually 0.5 - 2% of the occupied space.

Another possibility is that you are using a Software RAID - like Windows offers it - which spreads the data with redundancy over several disks. These disks will appear as one logical volume and the failure of a single disk will not cause any data loss. But for storing the redundant information additional space is needed, which cannot be used for user data.

A special characteristics of Offline Files can lead to wrong values for the allocated space of stub files. To avoid this, either ensure that the user which runs the scans has full read access to the scanned file system.

Another possibilty has been introduced with Windows 10 version 1903, the system reserverd storage. This space occupies about 7 GB by default and is used by Windows exclusively. It is not visible to other applications and currently not represented with the scan. You can check the size of the reserved storage in the "Storage Settings".

Since TreeSize holds file information of scanned directory structures in your system's RAM, the theoretical maxiumum disk size that can be scanned or searched by TreeSize is only limited by your systems memory. The same is true for exporting.

You can reduce the memory consumption of TreeSize by turning off the statistics for users, file types of age of files at "Tools > Options > Scan".


We offer another disk space manager called SpaceObServer which is designed for large servers and continuous reporting on enterprise level. It regularly collects the file system information using a background service and stores it in a SQL database, including size development and (optionally) all permissions. The reporting is faster and more flexible compared to TreeSize, because it is built on a database and collects data on file level. SpaceObServer "post scan actions" allow you to automatize cleanup and archiving tasks. If you are interested, please visit: https://www.jam-software.com/spaceobserver/
For an article on our blog discussing the topic, pleaser follow this link.

The user interface is similar to TreeSize. A client software as well as a web client are also available. This web client can be useful if you would like to make the collected data available to many end users without the need to install software on their machines.

Since Windows Vista and later, Microsoft enforces more strict security rules on the operating system. One side effect of this is that you may not see your mapped network drives anymore (Windows 8 and later), or they all appear disconnected (typically in Windows Vista and 7) in all applications that run with administrator privileges.

This is because Windows uses different user environments for non-elevated and elevated processes. There are some workarounds to gain access to those network drives anyway:

  • Do not run TreeSize as administrator unless it is truly needed.
  • Manually enter the UNC path (e.g. "\\server\share") for the network drive into the path drop-down list or target selection dialog and press enter.
  • Map the network drive in the context of the administrator using an elevated command prompt (run CMD as administrator). You can list the mapped drives using net use
    Type net use /? for more instructions on how to map the drive.
  • [Professional/Personal only] Use the "Map network drive" or "Add drive or UNC path" dialog from the Drive List menu bar.
  • [Not recommended because of security bypasses!] Enable "Linked Connections" as described here.

This is a known issue with Windows' preinstalled PDF file handler in combination with certain PDF files.

In order to be able to read the content of certain files, our software uses file handlers that are registered in Windows. Unfortunately, there seems to be an issue with Microsoft's PDF file handler, which causes this behavior in rare cases.

The same technology is also used by Windows' File Explorer (you could reproduce this issue in File Explorer as well). What you can do as a workaround is to install a different, third party file handler for PDF files, such as the one from Adobe.

Yes, to get a full report in Excel  in TreeSize, you need to check-mark the option "Tools > Options > Export > Excel > Export the full directory branch" and "Include single files in export". Then choose "File > Export > Excel File".

For other file types, please replace Excel with one of the other supported file types like CSV or PDF in the above instructions.

The full version of TreeSize Professional can be installed on an USB stick and can be run from there. To install TreeSize Professional as "portable edition", install it normally on a PC, run TreeSize and click "Tools > Create portable edition".

Scanning a drive via network is normally much slower than scanning a local disk because speed of the network is much lower, latency and overhead are higher compared to a local hard disk. Additionally, server drives are usually much bigger and contain more files than local hard disks.

So if possible try running TreeSize directly on the server. Alternatively you may try to turn off the users statistics at "Tools > Options > Scan > General > Statisitics" to speed up the scan.

You can also use scheduled Scans to perform your scans overnight. Network drives and command line options are supported by the Professional Edition only. 

For continuous analyzing of disk usage on large servers we recommend our product SpaceObServer. It collects the data using a background agent and stores it in a SQL database. It uses less RAM than TreeSize, and it offers more flexible reporting capabilities like historical development because it is built on a database. More information is available at: https://www.jam-software.com/spaceobserver/

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