Also known as: Mountain Time (MT) and Mountain Standard Time (MST)
Mountain Daylight Time (MDT) is 6 hours behind Coordinated Universal Time (UTC). This time zone is a Daylight Saving Time time zone and is used in: North America.
What Is Mountain Daylight Time?
Mountain Daylight Time is the second westernmost time zone in the United States and Canada. It is also used in Mexico.
It covers all or parts of 13 states in the US and five provinces or territories in Canada.
The MST time zone is the least populated time zone in the USA. It spans from northern Canada to Mexico.
In North America, Mountain Daylight Time shares a border with Central Daylight Time (CDT) in the east and with Pacific Daylight Time (PDT) in the west.
MDT or MST?
Mountain Daylight Time (MDT) is a North American time zone in use from the second Sunday in March to the first Sunday in November during Daylight Saving Time (DST). Mountain Standard Time (MST) is used during the remainder of the year.
MDT Is the Mountain Time Zone
In everyday usage, MDT is often referred to as Mountain Time (MT) or the Mountain Time Zone. This can add a bit of confusion as the term Mountain Time does not differentiate between standard time and Daylight Saving Time, so Mountain Time switches between MST and MDT in areas that use DST during part of the year.
Most North American time zones also have generic terms, including Pacific Time (PT), Central Time (CT), Eastern Time (ET), and Atlantic Time (AT).
Converting Mountain Time to Other US Time Zones
- Mountain Daylight Time (MDT) is 2 hours behind Eastern Daylight Time (EDT).
To convert MDT to EDT, you have to add two hours. - Mountain Daylight Time (MDT) is 1 hour behind Central Daylight Time (CDT).
To convert MDT to CDT, you have to add one hour. - Mountain Daylight Time (MDT) is 1 hour ahead of Pacific Daylight Time (PDT).
To convert MDT to PDT, you have to subtract one hour.
Time Zone Converter: UTC to MDT
Where and When is MDT Observed?
North America
US states using MDT in the summer and MST in the winter:
- Arizona - Navajo Nation only
- Colorado
- Idaho - most of the state except western counties Show
Benewah, Bonner, Boundary, Clearwater, Kootenai, Latah, Lewis, Nez Perce, Shoshone and north part of Idaho
- Kansas - some western counties only Show
Greeley, Hamilton, Sherman and Wallace
- Montana
- Nebraska - western counties Show
Arthur, Banner, Box Butte, Chase, Cheyenne, Dawes, Deuel, Dundy, Garden, Grant, Hooker, Keith, Kimball, Morrill, Perkins, Scotts Bluff, Sheridan, and Sioux and the western part of Cherry
- New Mexico
- North Dakota - South-Western parts Show
counties of Adams, Billings, Bowman, Golden Valley, Grant, Hettinger, Mercer, Slope and Stark, and southern parts of Dunn and McKenzie, most of Morton and Sioux counties
- Oregon - parts of Malheur county only Show
- South Dakota - western counties Show
Bennett, Butte, Corson, Custer, Dewey, Fall River, Haakon, Harding, Jackson, Lawrence, Meade, Pennington, Perkins, Shannon, and Ziebach, and the western parts of Stanley
- Texas - a few counties in west Show
El Paso and Hudspeth and part of Culberson
- Utah
- Wyoming
Canadian provinces/territories using MDT in the summer and MST in the winter:
- Alberta
- British Columbia - a few eastern communities Show
Cranbrook, Golden, Invermere
- Northwest Territories
- Nunavut - Kugluktuk, Cambridge Bay only (Other parts use EST/EDT or EST only)
- Saskatchewan - only Lloydminster
Mexican states using MDT in the summer and MST in the winter:
Other Time Zones in UTC -6
Some time zones exist that have the same offset as MDT, but can be found under a different name:
