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MDT/MST
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Mountain Time is on daylight saving time: MDT (UTC−6) until Sun, Nov 1.

Arizona stays on MST (UTC−7).

S
UTC−6
same time
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Quick answers

Selected conversion

6:00 am06:00 MDT (UTC-6), Oct 14, 2026 = 6:00 am06:00 S (UTC-6), Oct 14, 2026

MDT and S have the same local time.

MST and S examples

These examples always use MST (UTC-7) and S (UTC-6). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.

MST is 1 hour behind S.

Most of Arizona stays on MST (UTC-7) all year. Places such as Denver use MDT (UTC-6) during daylight saving time, one hour later. For daylight-time examples, use MDT to S.

How the time difference changes

For most of the year, MDT and S have the same time. From Nov 1, 2026 to Mar 14, 2027, MST is 1 hour behind S.

For most of the year, working hours of 9:00 am to 5:00 pm in MDT correspond to 9:00 am to 5:00 pm in S. At other times of the year, working hours of 9:00 am to 5:00 pm in MST correspond to 10:00 am to 6:00 pm in S.For most of the year, working hours of 09:00 to 17:00 in MDT correspond to 09:00 to 17:00 in S. At other times of the year, working hours of 09:00 to 17:00 in MST correspond to 10:00 to 18:00 in S.

Compare MST time with S time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.

Time Difference

Mountain Daylight Time and Sierra Time Zone have the same local time.
6:00 am06:00 in MDT is 6:00 am06:00 in S

MDT to S call time
Best time for a conference call or a meeting is between 9am-5pm09:00-17:00 in MDT which corresponds to 9am-5pm09:00-17:00 in S

6:00 am06:00 Mountain Daylight Time (MDT). Offset UTC -6:00 hours
6:00 am06:00 Sierra Time Zone (S). Offset UTC -6:00 hours

6:00 am06:00 MDT / 6:00 am06:00 S

Choose an hour to update the converter. Day labels such as “next day” or “+1” are relative to the selected date in the first column. Use Up and Down arrow keys, Home or End to move between hours, then Enter or Space to select.

Hourly time comparison
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Mountain Standard Time

Offset: MST is 7 hours behind Greenwich Mean Time (GMT).

Countries using this time zone: Canada, Mexico, United States

Principal Cities: The largest city in the MST time zone is Phoenix in the United States, with about 1.65 million people. Other major cities in this time zone include Ciudad Juárez, Calgary, Edmonton, Hermosillo.

French: HNR - Heure Normale des Rocheuses

Spanish: MT - Zona Pacífico

Map of the areas on Mountain Standard Time (MST)
MST all year MST part of the year

Today the lighter areas are on UTC−6 (MDT).

Daylight Saving: This is a standard time zone. During summer, some places set clocks forward one hour for daylight saving time and observe Mountain Daylight Time (MDT).

123456789101112End: Mountain Standard Time (MST) ended on Sunday, March 8, 2026 at 2:00 am02:00 local time and clocks were set one hour forward to Sunday, March 8, 2026, 3:00 am03:00 local daylight time instead. Standard time ends annually on the second Sunday of March.

123456789101112Start: Mountain Standard Time (MST) starts on Sunday, November 1, 2026 at 2:00 am02:00 local time and clocks are set one hour back to Sunday, November 1, 2026, 1:00 am01:00. Standard time starts annually on the first Sunday of November.

See upcoming clock changes worldwide.

MST representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • -07 - basic short
  • -0700 - basic
  • -07:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • -0700 - sign character (-) followed by a four digit time providing hours (07) and minutes (00) of the offset. Indicates an offset of seven hours to the west of the zero meridian.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Tango - Military abbreviation for MST
  • T - short form of 'Tango'
IANA/Olson: Reflects MST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Boise
  • America/Cambridge_Bay
  • America/Ciudad_Juarez
  • America/Creston
  • America/Dawson
  • America/Dawson_Creek
  • America/Denver
  • America/Edmonton
  • America/Fort_Nelson
  • America/Hermosillo
  • America/Inuvik
  • America/Mazatlan
  • America/Phoenix
  • America/Shiprock
  • America/Whitehorse
  • America/Yellowknife
  • Canada/Mountain
  • Canada/Yukon
  • MST
  • MST7MDT
  • Mexico/BajaSur
  • Navajo
  • US/Arizona
  • US/Mountain
Time zones with the GMT -7 offset:
  • MST - Mountain Standard Time
  • PDT - Pacific Daylight Time
  • YST - Yukon Standard Time
  • T - Tango Time Zone

Sierra Time Zone

Offset: S is 6 hours behind Greenwich Mean Time (GMT).

Daylight Saving: Some places on Sierra Time Zone (S) keep the same time all year, while others use S for only part of the year and change their clocks for daylight saving time; see upcoming clock changes worldwide.

Map of the areas on Sierra Time Zone (S)
S all year S part of the year

Today some of the lighter areas are on UTC−5 (Central Daylight Time).

S representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • -06 - basic short
  • -0600 - basic
  • -06:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • -0600 - sign character (-) followed by a four digit time providing hours (06) and minutes (00) of the offset. Indicates an offset of six hours to the west of the zero meridian.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Sierra - Military abbreviation for S
  • S - short form of 'Sierra'
Time zones with the GMT -6 offset:
  • CST - Central Standard Time
  • CT - Central Time
  • MDT - Mountain Daylight Time
  • EAST - Easter Island Standard Time
  • GALT - Galapagos Time
  • S - Sierra Time Zone