No overlap — one side will join outside working hours
JST (Tokyo)
MST (Denver)
00:00
09:00-1dWorking
01:00
10:00-1dWorking
02:00
11:00-1dWorking
03:00
12:00-1dWorking
04:00
13:00-1dWorking
05:00
14:00-1dWorking
06:00
15:00-1dWorking
07:00
16:00-1dWorking
08:00
17:00-1d
09:00Working
18:00-1doff
10:00Working
19:00-1doff
11:00Working
20:00-1doff
12:00Working
21:00-1doff
13:00Working
22:00-1doff
14:00Working
23:00-1doff
15:00Working
00:00off
16:00Working
01:00off
17:00
02:00
18:00
03:00
19:00
04:00
20:00
05:00
21:00
06:00
22:00
07:00
23:00
08:00
Working hours: 09:00–17:00 local. Green = both working.Purple = one side only.
Frequently Asked Questions
What is the difference between jst and mst?
Japan Standard Time (jst) is UTC+9 and Mountain Standard Time (mst) is UTC-6. The difference between them is 15 hours.
Where is jst used?
Japan Standard Time (jst) is used in Japan and surrounding regions. The IANA timezone identifier is Asia/Tokyo.
Where is mst used?
Mountain Standard Time (mst) is used in USA and surrounding regions. The IANA timezone identifier is America/Denver.
How do I convert jst to mst?
Use the interactive converter above. Drag the time slider to any jst time and the mst equivalent updates instantly. You can also type a time like "3pm" or "15:00" in the input bar.
JST (Tokyo) is 15 hours ahead of MST (Denver). At noon in JST (Tokyo), your contact in MST (Denver) sees 21:00.
JST (Tokyo) runs on Asia/Tokyo; MST (Denver) runs on America/Denver. Together they are 15 hours apart.
Shared working hours
There is no business hours overlap between JST (Tokyo) and MST (Denver) during standard working hours (9:00–17:00). Meetings would require one party to work outside normal hours.
Best call times between these locations
JST (Tokyo) and MST (Denver) have no shared working window. These slots minimize out-of-hours disruption for both sides.
07:00 Tokyo / 16:00 Denver⚡ One side off-hours
⚠️ 2h before working hours in Tokyo
09:00 Tokyo / 18:00 Denver⚡ One side off-hours
⚠️ 2h after working hours in Denver
06:00 Tokyo / 15:00 Denver⚡ 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.
JST (Tokyo)7 holidays
Jul 20Marine Day
Aug 11Mountain Day
Sep 21Respect for the Aged Day
Sep 23Autumnal Equinox Day
Oct 12Sports Day
MST (Denver)7 holidays
Jul 3Independence DaySOON
Sep 7Labour Day
Oct 12Columbus Day
Oct 12Indigenous Peoples' Day
Nov 11Veterans Day
Scheduling between JST (Tokyo) and MST (Denver)
A 15-hour difference separates JST (Tokyo) (Japan) and MST (Denver) (USA) — wide enough that standard business hours don't align at all. Scheduling requires deliberate compromise from both sides.
💡 Scheduling tips for these locations
⚡
A 07:00 meeting in JST (Tokyo) means 16:00 in MST (Denver) (2h before working hours in Tokyo).
⚡
A 09:00 meeting in JST (Tokyo) means 18:00 in MST (Denver) (2h after working hours in Denver).
⚡
A 06:00 meeting in JST (Tokyo) means 15:00 in MST (Denver) (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 JST (Tokyo)".
