Set hardware clock to UTC

Some OS like GNU/Linux and MacOS set up the hardware clock to use UTC instead of local time. This helps when dealing with daylight saving time, as the real clock does not need to be updated accordingly.

Windows expects the hardware clock to give “local time” by default. The reason is, according to Microsoft, so that users are not confused in BIOS menu (

To enable UTC real-time clock in Windows, put this in a .reg file:

Windows Registry Editor Version 5.00


Apply this file for example with a command like:

reg import utc-clock.reg

Or directly set the value with:

reg add HKLM\SYSTEM\CurrentControlSet\Control\TimeZoneInformation /v RealTimeIsUniversal /t REG_DWORD /d 1

To check the current config, you can use:

> reg query HKLM\SYSTEM\CurrentControlSet\Control\TimeZoneInformation /v RealTimeIsUniversal

    RealTimeIsUniversal    REG_DWORD    0x1