ACST to MDT Converter
South Australia is on daylight saving time: ACDT (UTC+10:30) until Sun, Apr 4, 2027.
The Northern Territory stays on ACST (UTC+9:30).
Mountain Time is on standard time: MST (UTC−7) until Sun, Mar 14, 2027.
Start by searching for a time zone, city, or town.
Add one or more places to compare local times, adjust the date, and share the result.
Quick answers
Selected conversion
1:30 am01:30 ACST (UTC+9:30), Nov 2, 2026 = 9:00 am09:00 MST (UTC-7), Nov 1, 2026
ACST is 16 hours and 30 minutes ahead of MST.
ACST and MDT examples
These examples always use ACST (UTC+9:30) 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.
ACST is 15 hours and 30 minutes ahead of MDT.
How the time difference changes
For most of the year, ACST is 15 hours and 30 minutes ahead of MDT. From Nov 1, 2026 to Mar 14, 2027, ACST is 16 hours and 30 minutes ahead of MST.
For most of the year, working hours of 9:00 am to 6:00 pm in ACST correspond to 5:30 pm (previous day) to 2:30 am in MDT. At other times of the year, working hours of 9:00 am to 6:00 pm in ACST correspond to 4:30 pm (previous day) to 1:30 am in MST.For most of the year, working hours of 09:00 to 18:00 in ACST correspond to 17:30 (previous day) to 02:30 in MDT. At other times of the year, working hours of 09:00 to 18:00 in ACST correspond to 16:30 (previous day) to 01:30 in MST.
Compare ACST time with MDT time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.
Time Difference
Australian Central Standard Time is 16 hours and 30 minutes ahead of Mountain Standard Time.
1:30 am01:30 in ACST is 9:00 am09:00 in MST
ACST to MST call time
Best time for a conference call or a meeting is between 9am-10:30am09:00-10:30 in ACST which corresponds to 4:30pm-6pm16:30-18:00 in MST (previous day)
1:30 am01:30 Australian Central Standard Time (ACST). Offset UTC +9:30 hours
9:00 am09:00 Mountain Standard Time (MST). Offset UTC -7:00 hours
1:30 am01:30 ACST / 9:00 am09:00 MST
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.
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Australian Central Standard Time
Offset: ACST is 9 hours and 30 minutes ahead of Greenwich Mean Time (GMT).
Countries using this time zone: Australia
Principal Cities: The largest city in the ACST time zone is Adelaide in Australia, with about 1.469 million people. Other major cities in this time zone include Darwin, Palmerston, Alice Springs, Mount Gambier.
Today the lighter areas are on UTC+10:30 (ACDT).
Daylight Saving: This is a standard time zone. During summer, some places set clocks forward one hour for daylight saving time and observe Australian Central Daylight Time (ACDT).
End: Australian Central Standard Time (ACST) ended on Sunday, October 4, 2026 at 2:00 am02:00 local time and clocks were set one hour forward to Sunday, October 4, 2026, 3:00 am03:00 local daylight time instead. Standard time ends annually on the first Sunday of October.
Start: Australian Central Standard Time (ACST) starts on Sunday, April 4, 2027 at 3:00 am03:00 local time and clocks are set one hour back to Sunday, April 4, 2027, 2:00 am02:00. Standard time starts annually on the first Sunday of April.
See Australia daylight saving time and upcoming clock changes worldwide.
ACST representations, usage and related time zones
- +0930 - basic
- +09:30 - extended
- +0930 - sign character (+) followed by a four digit time providing hours (09) and minutes (30) of the offset. Indicates an offset of nine hours and thirty minutes to the east of the zero meridian.
- Australia/Adelaide
- Australia/Broken_Hill
- Australia/Darwin
- Australia/North
- Australia/South
- Australia/Yancowinna
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 Denver, El Paso, Albuquerque, Colorado Springs.
French: HAR - Heure Avancée des Rocheuses
Spanish: MT - Zona Pacífico
Today the shaded areas are on UTC−7 (MST).
Daylight Saving: Mountain Daylight Time (MDT) is a daylight saving/summer time zone, but some places set clocks back one hour during winter and observe Mountain Standard Time (MST).
End: Mountain Daylight Time (MDT) ended on Sunday, November 1, 2026 at 2:00 am02:00 local time and clocks were 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.
Start: Mountain Daylight Time (MDT) starts on Sunday, March 14, 2027 at 2:00 am02:00 local time and clocks are set one hour forward to Sunday, March 14, 2027, 3:00 am03:00. Daylight saving starts annually on the second Sunday of March.
See USA daylight saving time and upcoming clock changes worldwide.
MDT representations, usage and related time zones
- -06 - basic short
- -0600 - basic
- -06:00 - extended
- -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.
- Sierra - Military abbreviation for MDT
- S - short form of 'Sierra'
- America/Boise
- America/Cambridge_Bay
- America/Ciudad_Juarez
- America/Denver
- America/Edmonton
- America/Inuvik
- America/Shiprock
- America/Yellowknife
- Canada/Mountain
- MST7MDT
- Navajo
- US/Mountain
- CST - Central Standard Time
- CT - Central Time
- MDT - Mountain Daylight Time
- EAST - Easter Island Standard Time
- GALT - Galapagos Time
- S - Sierra Time Zone