Convert MDT to ACST
ACST is 15 hours 30 minutes ahead of MDT. MDT is UTC−6 and ACST is UTC+9:30.
Right now: MDT · ACST
Best time to schedule a meeting
Standard 9–5 working hours do not overlap at all between MDT and ACST. Someone has to take an early or late call — or use asynchronous communication instead.
| MDT | ACST | Suitable? |
|---|---|---|
| 9:00 AM | 12:30 AM (next day) | outside 9–5 |
| 10:00 AM | 1:30 AM (next day) | outside 9–5 |
| 11:00 AM | 2:30 AM (next day) | outside 9–5 |
| 12:00 PM | 3:30 AM (next day) | outside 9–5 |
| 1:00 PM | 4:30 AM (next day) | outside 9–5 |
| 2:00 PM | 5:30 AM (next day) | outside 9–5 |
| 3:00 PM | 6:30 AM (next day) | outside 9–5 |
| 4:00 PM | 7:30 AM (next day) | outside 9–5 |
| 5:00 PM | 8:30 AM (next day) | outside 9–5 |
MDT to ACST conversion table
| MDT | ACST |
|---|---|
| 12:00 AM | 3:30 PM |
| 1:00 AM | 4:30 PM |
| 2:00 AM | 5:30 PM |
| 3:00 AM | 6:30 PM |
| 4:00 AM | 7:30 PM |
| 5:00 AM | 8:30 PM |
| 6:00 AM | 9:30 PM |
| 7:00 AM | 10:30 PM |
| 8:00 AM | 11:30 PM |
| 9:00 AM | 12:30 AM (next day) |
| 10:00 AM | 1:30 AM (next day) |
| 11:00 AM | 2:30 AM (next day) |
| 12:00 PM | 3:30 AM (next day) |
| 1:00 PM | 4:30 AM (next day) |
| 2:00 PM | 5:30 AM (next day) |
| 3:00 PM | 6:30 AM (next day) |
| 4:00 PM | 7:30 AM (next day) |
| 5:00 PM | 8:30 AM (next day) |
| 6:00 PM | 9:30 AM (next day) |
| 7:00 PM | 10:30 AM (next day) |
| 8:00 PM | 11:30 AM (next day) |
| 9:00 PM | 12:30 PM (next day) |
| 10:00 PM | 1:30 PM (next day) |
| 11:00 PM | 2:30 PM (next day) |
About MDT
Mountain Daylight Time (MDT) is UTC−6. It is used in Denver and Salt Lake City from March to November.
Mountain Daylight Time is UTC−6, the summer clock for Denver and Salt Lake City. During those months it coincides with Central Standard Time, which is a genuine source of confusion in a country that spans both: a meeting at "6pm MDT" and one at "6pm CST" are the same instant, but the second is not a time anyone is actually on in summer.
About ACST
Australian Central Standard Time (ACST) is UTC+9:30. It is used in Adelaide and Darwin in winter.
Australian Central Standard Time is UTC+9:30, half an hour behind the eastern states rather than a whole hour, which surprises people every time. South Australia moves to daylight saving in October and the Northern Territory does not, so Adelaide and Darwin share this offset for half the year and are an hour apart for the other half.
Does this gap change with the seasons?
This gap is seasonal. The abbreviations themselves are fixed offsets, but the region on MDT switches to MST (UTC−7) from November to March. So the 15.5-hour figure on this page is correct for the part of the year when both places are actually on these abbreviations, and changes by an hour outside it.
ACST does not shift, so the whole change comes from one side. A recurring meeting fixed in ACST will appear to move by an hour for everyone on the other side, twice a year, without anyone changing anything.
This is the reason scheduling systems store an IANA zone such as Region/City rather than an offset or an abbreviation: the zone knows its own rules and the offset does not.
Frequently asked questions
What time is 9:00 AM MDT in ACST?
9:00 AM MDT is 12:30 AM ACST (next day).
Is ACST ahead of MDT?
ACST is 15 hours 30 minutes ahead of MDT.
Which time zone does this use?
MDT is UTC−6 and ACST is UTC+9:30. Both abbreviations denote a single fixed offset, so this conversion never shifts with daylight saving — what changes is which abbreviation a place is using at the time.