No overlap — one side will join outside working hours
MST (Denver)
JST (Tokyo)
00:00
15:00Working
01:00
16:00Working
02:00
17:00
03:00
18:00
04:00
19:00
05:00
20:00
06:00
21:00
07:00
22:00
08:00
23:00
09:00Working
00:00+1doff
10:00Working
01:00+1doff
11:00Working
02:00+1doff
12:00Working
03:00+1doff
13:00Working
04:00+1doff
14:00Working
05:00+1doff
15:00Working
06:00+1doff
16:00Working
07:00+1doff
17:00
08:00+1d
18:00
09:00+1dWorking
19:00
10:00+1dWorking
20:00
11:00+1dWorking
21:00
12:00+1dWorking
22:00
13:00+1dWorking
23:00
14:00+1dWorking
Working hours: 09:00–17:00 local. Green = both working.Purple = one side only.
Frequently Asked Questions
What is the difference between mst and jst?
Mountain Standard Time (mst) is UTC-6 and Japan Standard Time (jst) is UTC+9. The difference between them is 15 hours.
Where is mst used?
Mountain Standard Time (mst) is used in USA and surrounding regions. The IANA timezone identifier is America/Denver.
Where is jst used?
Japan Standard Time (jst) is used in Japan and surrounding regions. The IANA timezone identifier is Asia/Tokyo.
How do I convert mst to jst?
Use the interactive converter above. Drag the time slider to any mst time and the jst equivalent updates instantly. You can also type a time like "3pm" or "15:00" in the input bar.
MST (Denver) to JST (Tokyo) — exact time difference
MST (Denver) is 15 hours behind JST (Tokyo). At noon in MST (Denver), your contact in JST (Tokyo) sees 03:00.
MST (Denver) runs on America/Denver; JST (Tokyo) runs on Asia/Tokyo. Together they are 15 hours apart.
Working hours overlap
There is no business hours overlap between MST (Denver) and JST (Tokyo) during standard working hours (9:00–17:00). Meetings would require one party to work outside normal hours.
Best call times between these locations
MST (Denver) and JST (Tokyo) have no shared working window. These slots minimize out-of-hours disruption for both sides.
16:00 Denver / 07:00 Tokyo⚡ One side off-hours
⚠️ 2h before working hours in Tokyo
18:00 Denver / 09:00 Tokyo⚡ One side off-hours
⚠️ 2h after working hours in Denver
15:00 Denver / 06:00 Tokyo⚡ One side off-hours
⚠️ 3h before working hours in Tokyo
Working hours defined as 09:00–17:00 local time for each location.
Public holidays for both locations
⚡ Holiday alerts for both locations, double-check schedules before confirming.
MST (Denver)7 holidays
Jul 3Independence DaySOON
Sep 7Labour Day
Oct 12Columbus Day
Oct 12Indigenous Peoples' Day
Nov 11Veterans Day
JST (Tokyo)7 holidays
Jul 20Marine Day
Aug 11Mountain Day
Sep 21Respect for the Aged Day
Sep 23Autumnal Equinox Day
Oct 12Sports Day
Scheduling between MST (Denver) and JST (Tokyo)
Working across MST (Denver) (USA) and JST (Tokyo) (Japan) is a challenge — the 15-hour difference means no shared business hours window under a standard schedule. Flexibility from at least one side is required.
💡 Scheduling tips for these locations
⚡
A 16:00 meeting in MST (Denver) means 07:00 in JST (Tokyo) (2h before working hours in Tokyo).
⚡
A 18:00 meeting in MST (Denver) means 09:00 in JST (Tokyo) (2h after working hours in Denver).
⚡
A 15:00 meeting in MST (Denver) means 06:00 in JST (Tokyo) (3h before working hours in Tokyo).
With no shared business hours, these slots distribute the scheduling burden as evenly as possible between both locations.
Avoid scheduling mistakes — especially around daylight saving changes. Use the ClockinSync Chrome Extension to instantly verify and compare both time zones directly in your browser, without manual calculations.
Need a specific time? Use the slider or type directly into the input bar — it understands "3pm", "15:30", and location-specific formats like "9am MST (Denver)".
