The short answer

6pm in Atlantic Standard Time is 3pm in Mountain Standard Time.

Atlantic Standard Time is 3 hours ahead of Mountain Standard Time. It falls outside the 9-to-5 in Atlantic Standard Time but lands inside working hours in Mountain Standard Time.

Atlantic Standard Time
6pm
Mountain Standard Time
3pm
Right now
8:24amADT · UTC-03:00 · Mon, Jun 22
5:24amMDT · UTC-06:00 · Mon, Jun 22
Read across to convert
Atlantic Standard Time
ADT · UTC-03:00
8:24am ☀
Mountain Standard Time
MDT · UTC-06:00
5:24am ☾
Pinned6pmAtlantic Standard Time=3pmMountain Standard Time
12amMon
9pmSun ·−1d
1am
10pmSun ·−1d
2am
11pmSun ·−1d
3am
12amMon
4am
1am
5am
2am
6am
3am
7am
4am
NOW
8am
5am
9am
WORK
6am
10am
WORK
7am
11am
WORK
8am
12pm
WORK
9am
WORK
1pm
WORK
10am
WORK
2pm
WORK
11am
WORK
3pm
WORK
12pm
WORK
4pm
WORK
1pm
WORK
5pm
2pm
WORK
PINNED
6pm
3pm
WORK
7pm
4pm
WORK
8pm
5pm
9pm
6pm
10pm
7pm
11pm
8pm
daylightnightworking hoursoverlap
Best time to meet
Best for a call
Atlantic Standard Time
12pm–5pm
=
Mountain Standard Time
9am–2pm
Popular conversions

Quick reference.

9amAtlantic Standard Time=6amMountain Standard Time
12pmAtlantic Standard Time=9amMountain Standard Time
3pmAtlantic Standard Time=12pmMountain Standard Time
5pmAtlantic Standard Time=2pmMountain Standard Time
9pmAtlantic Standard Time=6pmMountain Standard Time
In context

What each side covers.

Atlantic Standard Time
ADT · UTC-03:00
8:24am

Canada & Caribbean

Mountain Standard Time
MDT · UTC-06:00
5:24am
Cities on this clock

Frequently asked

Quick answers about converting between Atlantic Standard Time and Mountain Standard Time. Can't find what you need? Email [email protected].

What is the time difference between Atlantic Standard Time and Mountain Standard Time?
Atlantic Standard Time is 3 hours ahead of Mountain Standard Time right now. We always show the live, daylight-saving-correct difference, so this figure already accounts for whichever side is observing summer time today.
When it's 6pm in Atlantic Standard Time, what time is it in Mountain Standard Time?
6pm in Atlantic Standard Time is 3pm in Mountain Standard Time. It falls outside the 9-to-5 in Atlantic Standard Time but lands inside working hours in Mountain Standard Time. Use the hour-by-hour table above to read any other time across.
What's the best time for a call between Atlantic Standard Time and Mountain Standard Time?
12pm–5pm in Atlantic Standard Time lines up with 9am–2pm in Mountain Standard Time — both sides are inside a 9-to-5 working day.
Does this account for daylight saving time?
Yes. We track every clock change in both places, so the abbreviations you see — ADT and MDT — are the ones actually in effect right now, not a fixed all-year value. When either side changes its clocks, this page updates automatically.
Why is the date sometimes different on each side?
When two places are far enough apart, the same moment can fall on different calendar days. That is why some conversions are marked "previous day" or "next day" — it is the same instant in time, read off two clocks that crossed midnight at different points.