:: gmt.cmd  Display the current time in GMT (World Time)

@echo off
setlocal

set _key=HKLM\System\CurrentControlSet\Control\TimeZoneInformation

:: find offset from GMT in minutes
for /f "Tokens=3" %%G in ('reg query %_key% /V ActiveTimeBias^|FIND "REG_DWORD"') do ( 
   set /a _offset=%%G
)

::convert to hours
set /a _offset_hours=%_offset% / 60

:: Get current local time
FOR /f "tokens=*" %%G IN ('time/t') DO set _time=%%G
SET _hh=%_time:~0,2%
SET _mm=%_time:~3,2%

:: add offset to the current time 
set /a _hh=%_hh% + %_offset_hours%

:: display result
echo Local time: 
time/t
echo.
echo GMT time %_hh%:%_mm%