AEST to MST Time Converter
MST is 17 hours behind AEST. Eastern Australia is currently on AEDT (UTC+11:00), and The US Mountain states are currently on MDT (UTC-6:00).
Best Time to Call Between AEST and MST
Both zones are inside normal business hours between 9:00 AM and 10:00 AM AEST — that's 4:00 PM to 5:00 PM MST. That's a 1-hour window.
both at work AEST only MST only neither — hours along the strip are AEST.
Common Times Converted
AEST on the left, MST on the right.
AEST to MST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| AEST | MST | Working hours |
|---|---|---|
| 12:00 AM | 7:00 AM prev day | — |
| 1:00 AM | 8:00 AM prev day | — |
| 2:00 AM | 9:00 AM prev day | MST only |
| 3:00 AM | 10:00 AM prev day | MST only |
| 4:00 AM | 11:00 AM prev day | MST only |
| 5:00 AM | 12:00 PM prev day | MST only |
| 6:00 AM | 1:00 PM prev day | MST only |
| 7:00 AM | 2:00 PM prev day | MST only |
| 8:00 AM | 3:00 PM prev day | MST only |
| 9:00 AM | 4:00 PM prev day | Both zones |
| 10:00 AM | 5:00 PM prev day | AEST only |
| 11:00 AM | 6:00 PM prev day | AEST only |
| 12:00 PM | 7:00 PM prev day | AEST only |
| 1:00 PM | 8:00 PM prev day | AEST only |
| 2:00 PM | 9:00 PM prev day | AEST only |
| 3:00 PM | 10:00 PM prev day | AEST only |
| 4:00 PM | 11:00 PM prev day | AEST only |
| 5:00 PM | 12:00 AM | — |
| 6:00 PM | 1:00 AM | — |
| 7:00 PM | 2:00 AM | — |
| 8:00 PM | 3:00 AM | — |
| 9:00 PM | 4:00 AM | — |
| 10:00 PM | 5:00 AM | — |
| 11:00 PM | 6:00 AM | — |
What AEST and MST Actually Are
AEST — Australian Eastern Standard Time
Sydney, Melbourne, Brisbane, Canberra, Hobart. Standing at UTC+10:00 as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, April 4, 2027, to AEST. Sydney and Melbourne move to AEDT (UTC+11) for the southern summer; Brisbane does not change at all.
Queensland abandoned daylight saving after a 1992 referendum, so for five months a year Brisbane and Sydney read different clocks despite sharing a zone.
MST — Mountain Standard Time
Denver, Salt Lake City, Calgary — and Phoenix year-round. Standing at UTC-7:00 as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, November 1, 2026, to MST. Arizona stays on MST all year, so Phoenix and Denver are an hour apart for eight months and identical for four.
Arizona has stayed on MST year-round since 1968 — the Navajo Nation within it does observe daylight saving, making the state a patchwork.
What This Means in Practice
The date changes mid-working-day
For 8 of the eight hours in a normal AEST working day, the equivalent MST time falls on a different calendar date. Anything scheduled in that stretch needs the date checked as well as the time, or a Tuesday call quietly becomes a Wednesday one at the other end.
Both sides change clocks, on different dates
Both regions observe daylight saving but do not switch on the same day, so for a week or two each spring and fall the gap between them is an hour different from the rest of the year. Those short windows are where recurring invitations quietly break.
Nearly opposite sides of the clock
At 17 hours apart, one side's morning is the other side's night. Handing work over at the end of a shift usually beats trying to get both parties in the same call.
Major Cities in Each Zone
Cities on AEST
Cities on MST
Frequently Asked Questions
What is the time difference between AEST and MST?
MST is 17 hours behind AEST.
What is 9:00 AM AEST in MST?
9:00 AM AEST is 4:00 PM the previous day MST.
What are the best hours to schedule a call between AEST and MST?
Between 9:00 AM and 10:00 AM AEST, which is 4:00 PM to 5:00 PM MST. Both sides are inside normal business hours through that window.
Does the difference between AEST and MST change during the year?
Yes. Both regions observe daylight saving, and they do not switch on the same dates, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, April 4, 2027.
Does AEST always mean Australian Eastern Standard Time?
Sydney and Melbourne move to AEDT (UTC+11) for the southern summer; Brisbane does not change at all.
Does MST always mean Mountain Standard Time?
Arizona stays on MST all year, so Phoenix and Denver are an hour apart for eight months and identical for four.