Microsoft DOS mem command

Updated: 04/26/2017 by Computer Hope

About mem

Allows you to determine the available, used, and free memory.

Tip: Users who are using Windows Vista, 7, 8, or later should use the below document for determining how much memory (RAM) is in the computer instead of using the mem command.


The mem command is an external command that is available in the below Microsoft operating systems as mem.exe.

MS-DOS 4.0 and above
Windows 95
Windows 98
Windows ME
Windows NT
Windows 2000
Windows XP

Mem syntax

Displays the amount of used and free memory in your system.

MEM [/CLASSIFY | /DEBUG | /FREE | /MODULE module name] [/PAGE]

/CLASSIFY or /C Classifies programs by memory usage. Lists the size of programs, provides a summary of memory in use, and lists largest memory block available.
/DEBUG or /D Displays status of all modules in memory, internal drivers, and other information.
/FREE or /F Displays information about the amount of free memory left in both conventional and upper memory.
/MODULE or /M Displays a detailed listing of a module's memory use. This option must be followed by the name of a module, optionally separated from /M by a colon.
/PAGE or /P Pauses after each screen full of information.

Mem examples


This command would display information about your memory as seen in the examples below.

Microsoft Windows 95 and Windows 98 example output:

Memory type Total Used Free
--------------- ------ ------ -----
Conventional 640 k 52 k 588 k
Upper 0 k 0 k 0 k
Reserved 384 k 384 k 0 k
Extended (XMS) 31,744 k 168 k 31,576 k
--------------- ------ ------ ------
Total memory 31,768 k 168 k 31,576 k
Total under 1 MB 640 k 52 k 588 k

Total Expanded (EMS)                    32 M (33,046,528 bytes) 
Free Expanded (EMS)                     16 M (16,777,216 bytes) 

Largest executable program size       588 K (602,512 bytes) 
Largest free upper memory block         0 K        (0 bytes) 
MS-DOS is resident in the high memory area.

Windows 2000 and Windows XP example output:

655360 bytes total conventional memory
655360 bytes available to MS-DOS
633872 largest executable program size
1048576 bytes total contiguous extended memory
0 bytes available contiguous extended memory
941056 bytes available XMS memory MS-DOS resident in High Memory Area

mem /f

Display the amount of conventional memory free.

Mem issues

When using the mem /c command from a DOS window in Windows no upper blocks will be seen, as shown in the above example. In Windows 0 bytes are shown because Windows reserves all global upper memory blocks for Windows.

MS-DOS 6.2 and above will not accept or recognize more than 64 MB of ram when typing mem.

Additional information