If you like to schedule your time in 15-minute increments, you may want to customize the Outlook Calendar to show appointments that way.
In Day or Work Week view, you may have noticed that Outlook shows you time in half-hour increments. You don't have to live with that. For example, if you prefer to schedule your time in 15-minute increments, you can make Outlook reflect that scheduling preference. It's easy to change the calendar grid so that it displays lines between the hours for different increments of time.
Be aware that when you make an entry in your calendar, the default duration will be the same as the time increment that you select for the display. That is, if you select 15 Minutes for the display, the default duration for each new appointment that you create will be 15 minutes. You can easily change the duration of the appointment by changing its end time or by selecting the desired block of time when you create the appointment.
It's also possible to display time by using a 24-hour clock (instead of the 12-hour clock that is the default for the United States). However, if you want to do this, you need to make a change to the regional settings for your computer. Making such a change will affect all programs on your computer that rely on the system clock. For more information, see Switch Calendar views between 12-hour and 24-hour clock.