How many hours is MST behind AEDT?
As abbreviations, AEDT is always 18 hours ahead of MST: MST is UTC−7 and AEDT is UTC+11. To convert, add 18 hours.
Check which label you actually need: MST (Mountain Time is on MDT today) and AEDT (Australian Eastern Time is on AEST today). A time written with an abbreviation that is not in use is usually meant as the local time, so convert between the places instead: right now AEDT is 16 hours ahead of MST.
When the MST to AEDT time difference changes
For most of the year AEDT is 16 hours ahead of MST. From 4 October to 31 October 2026, AEDT is 17 hours ahead of MST instead, because the two places change their clocks on different dates. Meetings booked by the usual gap land an hour off in those weeks.
| Dates | AEDT vs MST | Length |
|---|---|---|
| 5 April 2026 to 3 October 2026 | 16 hours ahead | 182 days |
| 4 October 2026 to 31 October 2026 | 17 hours ahead | 28 days |
| 1 November 2026 to 31 December 2026 | 18 hours ahead | 61 days |
| 1 January 2027 to 13 March 2027 | 18 hours ahead | 72 days |
| 14 March 2027 to 3 April 2027 | 17 hours ahead | 21 days |
| 4 April 2027 to 2 October 2027 | 16 hours ahead | 182 days |
| 3 October 2027 to 6 November 2027 | 17 hours ahead | 35 days |
| 7 November 2027 to 31 December 2027 | 18 hours ahead | 55 days |
Calling hours for MST and AEDT
- When AEDT is 16 hours ahead of MST: no shared 09:00 to 17:00 hours; try 17:00 in MST (09:00 in AEDT).
- When AEDT is 18 hours ahead of MST: no shared 09:00 to 17:00 hours; one side has to take the call outside office hours.
- When AEDT is 17 hours ahead of MST: no shared 09:00 to 17:00 hours; one side has to take the call outside office hours.