Skip to content
Tutorial Reference

How to Get the BIOS Boot Mode (UEFI or Legacy) in Batch Script

Learn reliable methods to detect UEFI vs. Legacy BIOS boot mode in Windows using Batch scripts, including environment variables, registry checks, and WMI lookups for accurate system administration.

Understanding whether a Windows machine booted in UEFI mode or Legacy BIOS mode is a critical prerequisite for many system administration tasks. Disk partitioning schemes (GPT vs. MBR), bootloader configurations, Secure Boot status, and OS deployment strategies all depend on the active firmware mode. A deployment script that assumes UEFI on a Legacy BIOS machine, or vice versa, will inevitably fail.

In this guide, we will explore multiple methods to detect the current boot mode from within a Batch Script, ranging from environment variable checks to registry queries and WMI lookups.

Method 1: The FIRMWARE_TYPE Environment Variable (Windows 10+)

Starting with Windows 10, Microsoft introduced the %FIRMWARE_TYPE% environment variable, which directly reports the firmware mode used during the last boot sequence.

@echo off
setlocal

echo Checking Boot Mode via Environment Variable...
echo.

if defined FIRMWARE_TYPE (
    echo Firmware Type: %FIRMWARE_TYPE%

    if /i "%FIRMWARE_TYPE%"=="UEFI" (
        echo [RESULT] This system booted in UEFI mode.
    ) else if /i "%FIRMWARE_TYPE%"=="Legacy" (
        echo [RESULT] This system booted in Legacy BIOS mode.
    ) else (
        echo [RESULT] Unknown firmware type: %FIRMWARE_TYPE%
    )
) else (
    echo [WARNING] FIRMWARE_TYPE variable is not defined.
    echo This may be an older Windows version. Try Method 2 or 3.
)

pause

Why This is the Preferred Method

The %FIRMWARE_TYPE% variable is populated by the Windows kernel itself during boot and is guaranteed to be accurate. It requires zero external commands, making it the fastest and most efficient check available.

Method 2: Checking the SecureBoot Registry Key

While the presence of Secure Boot does not technically guarantee UEFI (you could have UEFI without Secure Boot), the existence of the Secure Boot registry key itself is a strong indicator that the machine uses UEFI firmware.

@echo off
setlocal

echo Checking Boot Mode via Secure Boot Registry...

:: The SecureBoot State key only exists on UEFI systems
set "sb_key=HKLM\SYSTEM\CurrentControlSet\Control\SecureBoot\State"

reg query "%sb_key%" /v UEFISecureBootEnabled >nul 2>&1

if %errorlevel% equ 0 (
    :: The key exists - this is a UEFI system. Read the Secure Boot value.
    set "sb_val="
    for /f "tokens=2*" %%A in ('reg query "%sb_key%" /v UEFISecureBootEnabled 2^>nul ^| findstr /i "REG_DWORD"') do set "sb_val=%%B"

    echo [RESULT] System is UEFI.
    if "!sb_val!"=="0x1" (
        echo Secure Boot: ENABLED
    ) else (
        echo Secure Boot: DISABLED (but UEFI firmware is active^)
    )
) else (
    echo [RESULT] Secure Boot registry key not found.
    echo System is likely booted in Legacy BIOS mode.
    echo (Or UEFI with Secure Boot completely unsupported by the firmware^)
)

pause

Method 3: Using BCDEDIT (The Boot Configuration Database)

The Boot Configuration Data (BCD) store contains detailed information about how the system was booted. By querying bcdedit, we can examine the boot manager path, which differs between UEFI and Legacy boots.

@echo off
setlocal enabledelayedexpansion

:: Requires Admin
net session >nul 2>&1
if %errorlevel% neq 0 (
    echo [ERROR] Administrator privileges required for bcdedit.
    pause
    exit /b 1
)

echo Checking Boot Mode via BCD...
echo.

:: Dump BCD Boot Manager section
bcdedit /enum {bootmgr} > "%temp%\bcd.txt" 2>nul

if not exist "%temp%\bcd.txt" (
    echo [ERROR] Failed to read BCD.
    pause
    exit /b 1
)

:: Debug output (optional but useful)
echo ===== BCD OUTPUT =====
type "%temp%\bcd.txt"
echo ======================
echo.

:: Detect UEFI by presence of .efi
findstr /i "\.efi" "%temp%\bcd.txt" >nul

if %errorlevel% equ 0 (
    echo [RESULT] UEFI Boot Mode detected.
) else (
    echo [RESULT] Legacy BIOS Boot Mode detected.
)

del "%temp%\bcd.txt" >nul 2>&1

pause

How the Detection Works

On UEFI systems, the Windows Boot Manager resides at \EFI\Microsoft\Boot\bootmgfw.efi on the EFI System Partition. On Legacy BIOS systems, the path is simply \bootmgr on the System Reserved partition. Searching for the string "efi" in the boot manager path is a reliable way to distinguish between the two modes.

Method 4: Using PowerShell with GetFirmwareType API

For maximum reliability across all Windows versions that support PowerShell, we can call the GetFirmwareType Windows API directly. This avoids relying on environment variables (which may not exist on older systems) or indirect indicators like registry keys.

@echo off
setlocal

echo Checking Boot Mode via PowerShell/GetFirmwareType API...

set "mode="

for /f "delims=" %%A in ('powershell -NoProfile -Command "[uint32]$ft=0; $sig='[DllImport(\"kernel32.dll\")]public static extern bool GetFirmwareType(out uint firmwareType);'; Add-Type -MemberDefinition $sig -Name FW -Namespace Win32; if([Win32.FW]::GetFirmwareType([ref]$ft)){ if($ft -eq 2){'UEFI'} elseif($ft -eq 1){'Legacy'} else{'Unknown'} } else {'Unknown'}" 2^>nul') do set "mode=%%A"

if /i "%mode%"=="UEFI" (
    echo [RESULT] Boot Mode: UEFI
) else if /i "%mode%"=="Legacy" (
    echo [RESULT] Boot Mode: Legacy BIOS
) else (
    echo [RESULT] Boot Mode: Could not determine
)

pause

Method 5: Checking the System Disk Partition Style

UEFI systems typically use GPT (GUID Partition Table) disks, while Legacy BIOS systems use MBR (Master Boot Record). While this is not a 100% guarantee (you can have GPT on data disks in Legacy mode), the system disk's partition style is a strong indicator.

@echo off
setlocal enabledelayedexpansion

echo Checking System Disk Partition Style...

:: Requires Admin for diskpart
net session >nul 2>&1
if %errorlevel% neq 0 (
    echo [ERROR] Administrator privileges required for diskpart.
    pause
    exit /b 1
)

:: Determine which disk number contains the system partition
:: by examining the SystemDrive (usually C:)
set "sys_disk=0"
for /f "tokens=1" %%D in ('powershell -NoProfile -Command ^
  "(Get-Partition -DriveLetter ($env:SystemDrive[0])).DiskNumber" 2^>nul') do (
    set "sys_disk=%%D"
)

:: Use diskpart to query the system disk
set "tmpfile=%temp%\diskpart_check_%RANDOM%.txt"
(
    echo select disk %sys_disk%
    echo detail disk
) | diskpart > "%tmpfile%" 2>nul

findstr /i "GPT" "%tmpfile%" >nul
if !errorlevel! equ 0 (
    echo [RESULT] System disk (Disk %sys_disk%^) uses GPT partitioning.
    echo This strongly indicates UEFI boot mode.
) else (
    echo [RESULT] System disk (Disk %sys_disk%^) uses MBR partitioning.
    echo This strongly indicates Legacy BIOS boot mode.
)

del "%tmpfile%" 2>nul

pause

A Comprehensive Detection Script

Here is an all-in-one script that tries multiple methods and provides a confident assessment.

@echo off
setlocal enabledelayedexpansion

echo =============================================
echo       BOOT MODE DETECTION
echo =============================================
echo.

set "result=Unknown"
set "method=None"
set "is_admin=0"

:: Check admin rights once for methods that need it
net session >nul 2>&1
if !errorlevel! equ 0 set "is_admin=1"

:: Method 1: Environment Variable (fastest, no elevation needed)
if defined FIRMWARE_TYPE (
    set "result=%FIRMWARE_TYPE%"
    set "method=Environment Variable"
    echo Method 1 (Env Var^): %FIRMWARE_TYPE%
    goto :report
)
echo Method 1 (Env Var^): Not available (FIRMWARE_TYPE undefined^)

:: Method 2: Secure Boot Registry Key (no elevation needed)
reg query "HKLM\SYSTEM\CurrentControlSet\Control\SecureBoot\State" >nul 2>&1
if !errorlevel! equ 0 (
    set "result=UEFI"
    set "method=Secure Boot Registry"
    echo Method 2 (Registry^): SecureBoot key found - UEFI
    goto :report
)
echo Method 2 (Registry^): SecureBoot key not found

:: Method 3: BCDEDIT (requires admin)
if "!is_admin!"=="1" (
    set "bpath="
    for /f "tokens=2*" %%A in ('bcdedit /enum {bootmgr} 2^>nul ^| findstr /i "path"') do set "bpath=%%B"
    if defined bpath (
        echo !bpath! | findstr /i "efi" >nul
        if !errorlevel! equ 0 (
            set "result=UEFI"
        ) else (
            set "result=Legacy"
        )
        set "method=BCD Boot Path"
        echo Method 3 (BCD^):    !result! - path: !bpath!
        goto :report
    )
    echo Method 3 (BCD^):    Could not parse boot path
) else (
    echo Method 3 (BCD^):    Skipped (not running as Administrator^)
)

echo.
echo [WARNING] All detection methods were inconclusive.

:report
echo.
echo =============================================
echo   BOOT MODE: !result!
echo   Detected via: !method!
echo =============================================
pause

Common Mistakes

The Wrong Way: Assuming UEFI Based on Windows Version

:: WRONG - Windows 10 can run in Legacy BIOS mode
if exist "C:\Windows\System32" echo Must be UEFI

The Wrong Way: Using bcdedit Without Admin Rights

:: WRONG - bcdedit requires elevation
bcdedit /enum {bootmgr}

Running bcdedit as a standard user returns "Access is denied". Always check for admin rights before using this method, and prefer the %FIRMWARE_TYPE% variable when possible as it requires no elevation.

The Wrong Way: Relying Solely on the Secure Boot Registry Key

:: INCOMPLETE - Absence of the key does not definitively mean Legacy BIOS
reg query "HKLM\SYSTEM\...\SecureBoot\State" >nul 2>&1
if %errorlevel% neq 0 echo Definitely Legacy BIOS

Best Practices

  1. Try %FIRMWARE_TYPE% first: It is instant, requires no elevation, and works on Windows 10 1607+.
  2. Layer multiple methods: For maximum compatibility across Windows versions, check the environment variable first, then fall back to the registry, then bcdedit.
  3. Log the result: In deployment scripts, always record the detected boot mode to a log file so that post-deployment audits can verify the machine was configured for the correct firmware type.
  4. Report which method succeeded: When layering multiple detection methods, record which method produced the result. This aids troubleshooting when different methods disagree or when a method that should work returns unexpected results.
  5. Check admin rights once: If the script uses multiple methods that may or may not require elevation, check net session once at the top and store the result in a variable rather than checking repeatedly.

Conclusion

Detecting whether a Windows machine booted in UEFI or Legacy BIOS mode is fundamental for system administration scripts that handle disk partitioning, bootloader repair, or OS deployment. The %FIRMWARE_TYPE% environment variable provides the fastest and simplest detection on modern Windows. For broader compatibility, querying the Secure Boot registry key or parsing the bcdedit boot manager path offers reliable fallback methods. Combining all three approaches into a layered detection script guarantees accurate results across virtually any Windows installation.

Navigation