The abbreviation for Mountain Standard Time is MST.
Mountain Standard Time is the North American standard-time designation for UTC−07:00. It is used in parts of Canada, Mexico, and the United States, particularly across regions associated with the Rocky Mountains. The name refers to standard time, before any seasonal clock adjustment.
Many places in the Mountain Time Zone switch to Mountain Daylight Time, abbreviated MDT, during daylight saving time. MDT is UTC−06:00, one hour ahead of MST. Arizona is a notable exception: most of the state does not observe daylight saving time, so it generally remains on MST year-round.
MST is easy to confuse with EST, CST, and PST, but those refer to different North American zones. EST is UTC−05:00, CST is UTC−06:00, and PST is UTC−08:00. The abbreviation MST can also have other meanings in unrelated contexts, so a geographic label is useful when precision matters.