MST to AEST Time Converter
AEST is 17 hours ahead of MST. The US Mountain states are currently on MDT (UTC-6:00), and Eastern Australia is currently on AEDT (UTC+11:00).
Best Time to Call Between MST and AEST
Both zones are inside normal business hours between 4:00 PM and 5:00 PM MST — that's 9:00 AM to 10:00 AM AEST. That's a 1-hour window.
both at work MST only AEST only neither — hours along the strip are MST.
Common Times Converted
MST on the left, AEST on the right.
MST to AEST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| MST | AEST | Working hours |
|---|---|---|
| 12:00 AM | 5:00 PM | — |
| 1:00 AM | 6:00 PM | — |
| 2:00 AM | 7:00 PM | — |
| 3:00 AM | 8:00 PM | — |
| 4:00 AM | 9:00 PM | — |
| 5:00 AM | 10:00 PM | — |
| 6:00 AM | 11:00 PM | — |
| 7:00 AM | 12:00 AM next day | — |
| 8:00 AM | 1:00 AM next day | — |
| 9:00 AM | 2:00 AM next day | MST only |
| 10:00 AM | 3:00 AM next day | MST only |
| 11:00 AM | 4:00 AM next day | MST only |
| 12:00 PM | 5:00 AM next day | MST only |
| 1:00 PM | 6:00 AM next day | MST only |
| 2:00 PM | 7:00 AM next day | MST only |
| 3:00 PM | 8:00 AM next day | MST only |
| 4:00 PM | 9:00 AM next day | Both zones |
| 5:00 PM | 10:00 AM next day | AEST only |
| 6:00 PM | 11:00 AM next day | AEST only |
| 7:00 PM | 12:00 PM next day | AEST only |
| 8:00 PM | 1:00 PM next day | AEST only |
| 9:00 PM | 2:00 PM next day | AEST only |
| 10:00 PM | 3:00 PM next day | AEST only |
| 11:00 PM | 4:00 PM next day | AEST only |
What MST and AEST Actually Are
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.
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.
What This Means in Practice
The date changes mid-working-day
For 8 of the eight hours in a normal MST working day, the equivalent AEST 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 MST
Cities on AEST
Frequently Asked Questions
What is the time difference between MST and AEST?
AEST is 17 hours ahead of MST.
What is 9:00 AM MST in AEST?
9:00 AM MST is 2:00 AM the next day AEST.
What are the best hours to schedule a call between MST and AEST?
Between 4:00 PM and 5:00 PM MST, which is 9:00 AM to 10:00 AM AEST. Both sides are inside normal business hours through that window.
Does the difference between MST and AEST 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, November 1, 2026.
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.
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.