比通过 FOR 快 10 倍。具有能够使用 DIR 命令的任何允许参数(在本例中为 /S)的优势
@ECHO OFF
SET folder="C:\WINDOWS"
call:timer
ECHO Processing, please wait...
CALL :folderSize size %folder% "/S"
CALL :strNumDivide sizeKb %size% 1024
CALL :strNumDivide sizeMb %sizeKb% 1024
CALL :strNumDivide sizeGb %sizeMb% 1024
CALL :formatNumber size %size%
CALL :formatNumber sizeKb %sizeKb%
CALL :formatNumber sizeMb %sizeMb%
CALL :formatNumber sizeGb %sizeGb%
ECHO.
ECHO Size of %folder%: 
ECHO.
ECHO %size% bytes
ECHO %sizeKb% Kb
ECHO %sizeMb% Mb
ECHO %sizeGb% Gb
ECHO.
pause
exit /b
:: Function to calculate the size of a directory and its subdirectories
::----------------------------------------------------------------------
:folderSize <returnVariableName> <folder> [DIR parameters]
    SetLocal EnableExtensions EnableDelayedExpansion
    SET folder=%2
    SET params=%~3
    IF NOT DEFINED folder SET folder="%CD%"
    DIR %params% /W "%folder:"=%" > %TEMP%\folderSize.tmp
    FOR /F "tokens=1 delims=:" %%x IN ('findstr /n /e ":" %TEMP%\folderSize.tmp') DO (SET line=%%x)
    IF DEFINED line (
        SET /A line = !line! + 1
        FOR /F "tokens=4 delims= " %%i IN ('findstr /n "bytes" %TEMP%\folderSize.tmp^|findstr "!line!:"') DO (SET size=%%i)
        SET size=!size:.=!
    ) ELSE (
        FOR /F "tokens=3 delims= " %%i IN ('findstr /e "bytes" %TEMP%\folderSize.tmp') DO (SET size=%%i)
        SET size=!size:.=!
    )
    DEL %TEMP%\folderSize.tmp > nul
    EndLocal & SET "%~1=%size%"
GOTO:EOF
:: Extras functions to convert between different units and to give numerical format
:: --------------------------------------------------------------------------------
:strNumDivide <returnVariableName> <stringNum> <divisor>
    SetLocal EnableExtensions EnableDelayedExpansion 
    SET strNum=%~2
    SET divisor=%~3
    SET result=
    SET number=
    IF !divisor! EQU 0 GOTO:EOF
    FOR /L %%n IN (0,1,18) DO (
        IF NOT "!strNum:~%%n!" == "" (
            SET number=!number!!strNum:~%%n,1!
            IF !number! GEQ !divisor! (
                SET /A quotient=!number! / !divisor!
                SET /A number=!number! - !quotient! * !divisor!
                IF !number! EQU 0 SET number=
                SET result=!result!!quotient!
            ) ELSE (
                IF DEFINED result SET result=!result!0
            )
        )
    )
    IF NOT DEFINED result SET "result=0"
    EndLocal & SET "%~1=%result%"
GOTO:EOF
:formatNumber <returnVariableName> <number> [separator [group size]] 
    SetLocal EnableExtensions EnableDelayedExpansion 
    SET "raw=%~2"
    SET "separator=%~3" 
    SET "group=%~4" 
    SET "answer=" 
    IF NOT DEFINED raw GOTO :EOF
    IF NOT DEFINED separator SET "separator=."
    IF NOT DEFINED group SET "group=3"
    FOR %%g IN (-%group%) DO (
        FOR /F "tokens=1,2 delims=,." %%a IN ("%raw%") DO ( 
            SET int=%%a
            SET frac=%%b
            FOR /F "delims=:" %%c IN ('^(ECHO;!int!^& Echo.NEXT LINE^)^|FindStr /O "NEXT LINE"') DO (
                SET /A length=%%c-3
            ) 
            FOR %%c IN (!length!) DO ( 
                SET radix=!raw:~%%c,1!
            )
            FOR /L %%i IN (!length!, %%g, 1) DO ( 
                SET answer=!int:~%%g!!separator!!answer! 
                SET int=!int:~0,%%g!
            ) 
        ) 
    )
    SET answer=%answer: =%
    SET answer=%answer:~0,-1%
    EndLocal & SET "%~1=%answer%%radix%%frac%" 
Goto :EOF 
结果输出示例:(在示例中,例程用了 3 秒计算了大小为 28GB 的 C:\WINDOWS 的大小)
Processing, please wait...
Size of "C:\WINDOWS":
30.936.389.769 bytes
30.211.318 Kb
29.503 Mb
28 Gb
Elapsed Time: 3 secs