Updating current time…
S
12am
3am
6am
9am
12pm
3pm
6pm
9pm
MDT
UTC−6
same time
12am
3am
6am
9am
12pm
3pm
6pm
9pm

Quick answers

Selected conversion

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

S and MDT have the same local time.

S and MDT examples

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

S and MDT have the same local time.

How the time difference changes

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

For most of the year, working hours of 9:00 am to 5:00 pm in S correspond to 9:00 am to 5:00 pm in MDT. At other times of the year, working hours of 9:00 am to 5:00 pm in S correspond to 8:00 am to 4:00 pm in MST.For most of the year, working hours of 09:00 to 17:00 in S correspond to 09:00 to 17:00 in MDT. At other times of the year, working hours of 09:00 to 17:00 in S correspond to 08:00 to 16:00 in MST.

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

Time Difference

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

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

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

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

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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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

Mountain Daylight Time

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

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

Principal Cities: The largest city in the MDT time zone is Ciudad Juárez in Mexico, with about 1.512 million people. Other major cities in this time zone include Calgary, Edmonton, Denver, El Paso.

French: HAR - Heure Avancée des Rocheuses

Spanish: MT - Zona Pacífico

Map of the areas on Mountain Daylight Time (MDT)
MDT part of the year

Today all shaded areas are on MDT.

Daylight Saving: Mountain Daylight Time (MDT) is a daylight saving/summer time zone. During winter, some places set clocks back one hour and observe Mountain Standard Time (MST).

123456789101112Start: Mountain Daylight Time (MDT) started 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. Daylight saving starts annually on the second Sunday of March.

123456789101112End: Mountain Daylight Time (MDT) ends 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 local standard time instead. Daylight saving ends annually on the first Sunday of November.

See upcoming clock changes worldwide.

MDT 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 MDT
  • S - short form of 'Sierra'
IANA/Olson: Reflects MDT 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/Denver
  • America/Edmonton
  • America/Inuvik
  • America/Shiprock
  • America/Yellowknife
  • Canada/Mountain
  • MST7MDT
  • Navajo
  • US/Mountain
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