If you are like me, then you probably spend a lot of time in your Calendar app, with all the scheduling, appointments, tasks, etc. Here’s the deal, depending on your location and specific everyday’s environment, the default Calendar behavior will not suit you. Most of us run into these two problems: either your working days, working hours or both don’t match the defaults. Here’s how to change them (be carefull, wrong values in the registry can cause system instability of failure):

Grab a registry editor, like the free PHM Registry Editor, and navigate to the key: HKLMSoftwareMicrosoftCalendarActiveTimes

Inside, you will see an ActiveTimes entry, which you need to change as follows to suit your needs:

Monday – Friday, 8am to 5pm:

2210003E (DWORD hexadecimal)

Monday – Friday, 9am to 5pm:

2212003E (DWORD hexadecimal)

Monday – Friday, 9am to 6pm:

2412003E (DWORD hexadecimal)

Monday – Saturday, 8am to 5pm:

2210007E (DWORD hexadecimal)

Monday – Saturday, 9am to 5pm:

2212007E (DWORD hexadecimal)

Monday – Saturday, 9am to 6pm:

2412007E (DWORD hexadecimal)

You can see in the screenshot, I work Monday to Saturday from 9am to 6pm (our work week starts Monday).