Mountain Standard Time to Japan Standard Time, with the offset for today's date rather than an average.
JST time
Japan Standard Time is ahead of Mountain Standard Time — noon in MST is 3:00 am in JST
MDT todayUTC-06:00
JST todayUTC+09:00
Working-hour overlap0 h
Common meeting hours converted from MST to JST
MST (Mountain Standard Time)
JST (Japan Standard Time)
Working hours in both?
7:00 am
10:00 pm
No
8:00 am
11:00 pm
No
9:00 am
12:00 am next day
No
10:00 am
1:00 am next day
No
11:00 am
2:00 am next day
No
12:00 pm
3:00 am next day
No
1:00 pm
4:00 am next day
No
2:00 pm
5:00 am next day
No
3:00 pm
6:00 am next day
No
4:00 pm
7:00 am next day
No
5:00 pm
8:00 am next day
No
6:00 pm
9:00 am next day
No
7:00 pm
10:00 am next day
No
8:00 pm
11:00 am next day
No
This calculator needs JavaScript to recalculate. The answer above was
worked out on 19 August 2026 and is correct for
that date; the site rebuilds every morning.
Rebuilt
· conventions last checked
Which zone this page means. MST is standard time only; MDT (UTC-6) applies from March to November. Arizona stays on MST all year. Japan does not observe daylight saving, so JST applies all year.
MST is behind JST by 15 hours today
On 19 August 2026, Mountain Standard Time is on MDT at
UTC-06:00 and Japan Standard Time is on JST at
UTC+09:00. The gap between them is
15 hours, with JST
ahead. So 9:00 am in MST is
12:00 am in JST, and 5:00 pm in MST is
8:00 am in JST. Going the other way, see JST to MST.
The gap is not constant, and that is the part that catches people out
Mountain Standard Time is currently observing daylight saving and changes next on 1 November 2026, when clocks go back an hour. Japan Standard Time does not observe daylight saving at all, so the whole of the seasonal change comes
from the MST side: the gap moves by an hour twice a year even though nothing changes in
Japan Standard Time.
When you can actually both be at work
Taking a working day as 9:00 am to 5:00 pm local at each end, there
are 0 overlapping hours
in a normal day. There is none: the two working days do not touch at all, so any live meeting between
Mountain Standard Time and Japan Standard Time has to sit outside somebody's normal hours. The table above shows
which end has the shorter stretch to give up.
Zone rules are set by legislation and change, sometimes at short notice. This page is
built against tzdata 2026a, last reviewed
2026-08-18. Quarterly. Zone rules change by legislation, sometimes at short notice. Version and review date are shown on every zone page. The converter above reads
your browser's own copy of the zone database, so if a rule has changed since this page was built the
live answer follows the new rule.
Every convention used above — whether the start date counts, how month ends are
clamped, which holidays close an office — is written out on the
methodology page, including the daylight-saving rules behind the 15-hour gap above.
The current offset is shown at the top of this page. It is computed for today's date rather than quoted as an average, because the two regions change their clocks on different dates and the gap is different for a few weeks each year.
Is MST the same as Mountain Standard Time all year?
Not necessarily. Standard time and summer time are separate zones with separate abbreviations, so much of the year the technically correct abbreviation is the daylight one. The page states which is in force on today's date.
When do the clocks change in these zones?
The next change date for each zone is shown in the result panel, along with what the offset becomes afterwards.
What is a good meeting time between MST and JST?
The business-hours overlap window is shown below the converter. Where there is no overlap the page says so rather than suggesting an impossible time.