Convert Atlantic Standard Time to Mountain Standard Time
Instantly convert Atlantic Standard Time (AST) to Mountain Standard Time (MST) with our free online calculator.
Atlantic Standard Time
01:20:59 AM
Wed, Jun 24 (AST)
Mountain Standard Time
10:20:59 PM
Tue, Jun 23 (MST)
Convert a Specific Time
24-Hour Comparison
| AST | MST |
|---|---|
| 12:00 AM | 9:00 PM(-1d) |
| 1:00 AM | 10:00 PM(-1d) |
| 2:00 AM | 11:00 PM(-1d) |
| 3:00 AM | 12:00 AM |
| 4:00 AM | 1:00 AM |
| 5:00 AM | 2:00 AM |
| 6:00 AM | 3:00 AM |
| 7:00 AM | 4:00 AM |
| 8:00 AM | 5:00 AM |
| 9:00 AM | 6:00 AM |
| 10:00 AM | 7:00 AM |
| 11:00 AM | 8:00 AM |
| 12:00 PM | 9:00 AM |
| 1:00 PM | 10:00 AM |
| 2:00 PM | 11:00 AM |
| 3:00 PM | 12:00 PM |
| 4:00 PM | 1:00 PM |
| 5:00 PM | 2:00 PM |
| 6:00 PM | 3:00 PM |
| 7:00 PM | 4:00 PM |
| 8:00 PM | 5:00 PM |
| 9:00 PM | 6:00 PM |
| 10:00 PM | 7:00 PM |
| 11:00 PM | 8:00 PM |
How to Convert Atlantic Standard Time to Mountain Standard Time
Formula
To convert Atlantic Standard Time (AST) to Mountain Standard Time (MST): Convert AST to MST
About Atlantic Standard Time (AST)
Atlantic Standard Time (AST, IANA: America/Halifax, America/Puerto_Rico) is the time zone for the Canadian Maritime provinces and most of the Caribbean, set at UTC-4:00. AST is observed in: Nova Scotia, New Brunswick, Prince Edward Island, Labrador (partially), Newfoundland's Labrador portion, eastern Quebec, Puerto Rico, US Virgin Islands, Bermuda, Anguilla, Antigua, Aruba, Barbados, British Virgin Islands, Curaçao, Dominica, Grenada, Guadeloupe, Martinique, Saint Lucia, Saint Vincent, Trinidad and Tobago, and Venezuela (since 2007). Canadian Maritime provinces observe AST in winter and switch to ADT = UTC-3:00 in summer per the Energy Policy Act-aligned Canadian schedule. The Caribbean territories (Puerto Rico, USVI, Bermuda) and US territories observe AST year-round without DST per their territorial governments. AST is the same offset as EDT (Eastern Daylight Time) during US summer months, so Halifax and New York are on the same clock in summer but Halifax is one hour ahead in winter.
About Mountain Standard Time (MST)
Mountain Standard Time (MST, IANA: America/Denver and America/Phoenix) is the time zone for the US Mountain region and most of Canada's Rocky Mountain provinces, set at UTC-7:00. MST is observed from the first Sunday in November to the second Sunday in March; the region switches to Mountain Daylight Time (MDT = UTC-6:00) for the remainder of the year — EXCEPT for the State of Arizona (excluding Navajo Nation), which stays on MST year-round per Arizona Revised Statutes §1-242. Major MST cities: Denver, Phoenix, Salt Lake City, Albuquerque, El Paso, Tucson, Calgary, Edmonton. MST covers Colorado, Utah, Wyoming, Montana, Idaho (most), New Mexico, Arizona, parts of Texas + Mexico (Sonora). Population ~17 million in the time zone. Affects: NORAD Cheyenne Mountain operations, Denver Mile-High Stadium NFL game scheduling, Colorado ski-resort lift-operating hours, US Bureau of Land Management permit operations, and the Mormon Tabernacle Choir broadcast schedule from Salt Lake City.