Display military time in Windows Vista
By default for distributions of Windows Vista set to English-US, the time is displayed in the system clock and elsewhere using the AM/PM, 12-hour based system. But Windows Vista's date and time settings allow you to customize the display of time any way you like. This tutorial shows you how to make Vista use 24 hours to display the time of day, also known as "military time."
Use military time in Windows Vista
Unlike other date and time settings in Windows Vista, you configure the time display options through the Regional and Language Options: this is because Windows uses your culture settings (e.g. English-US) to determine your default currency, time display format, etc. To access the regional and language options, click on the Start Button, and choose Run.
In the dialog box that opens, type intl.cpl and hit Enter (or click OK) - this will open the Regional and Language Options window. The Format tab, selected by default, is the one you need: click the Customize this format button.
In the Customize Regional Options dialog that opens, click on the Time tab.
In the Time format field, type HH:mm and click Apply. "HH" stands for hours in 24-hour format, the column (":") is the optional separator between hours and minutes (you do not need to enter a separator), and "mm" stands for minutes.
(By entering twice the letter H (hours) and twice the letter m (minutes), you are instructing Windows Vista to always display two digits for the time; in other words, a leading zero will be inserted if needed, and your hours and minutes will always show as a two-digit number.)
Display seconds in the clock in Windows Vista
If you want Windows Vista to display seconds in the clock, in addition to hours and minutes, simply type ":ss" (a separator plus two-digit seconds) at the end of the Time format field. Keep in mind that the seconds will keep changing live, which can become a bit distracting.
You can use the Apply button instead of OK to experiment with time formats. And this is how you use military time in Windows Vista.up ↑