The short answer
Japan Standard Time is 15 hours ahead of Mountain Time.
Japan Standard Time☀
9:27:37am
JST · UTC+09:00 · Fri, Sep 25
Mountain Time☾
6:27:37pm
MDT · UTC-06:00 · Thu, Sep 24
Read across to convert
Japan Standard Time
JST · UTC+09:00
Mountain Time
MDT · UTC-06:00
Click any row to pin that hour across both zones.
12amFri
9amThu ·−1d
WORK1am
10amThu ·−1d
WORK2am
11amThu ·−1d
WORK3am
12pmThu ·−1d
WORK4am
1pmThu ·−1d
WORK5am
2pmThu ·−1d
WORK6am
3pmThu ·−1d
WORK7am
4pmThu ·−1d
WORK8am
5pmThu ·−1d
NOW
9am
WORK6pmThu ·−1d
10am
WORK7pmThu ·−1d
11am
WORK8pmThu ·−1d
12pm
WORK9pmThu ·−1d
1pm
WORK10pmThu ·−1d
2pm
WORK11pmThu ·−1d
3pm
WORK12amFri
4pm
WORK1am
5pm
2am
6pm
3am
7pm
4am
8pm
5am
9pm
6am
10pm
7am
11pm
8am
daylightnightworking hoursoverlap
Best time to meet=
Closest workable window
Just outside the working window — early on one side, late on the other.
Japan Standard Time
7am–10am
Mountain Time
4pm–7pm
previous day
Popular conversions
Quick reference.
9amJapan Standard Time=6pmMountain Time · prev day
12pmJapan Standard Time=9pmMountain Time · prev day
3pmJapan Standard Time=12amMountain Time
5pmJapan Standard Time=2amMountain Time
9pmJapan Standard Time=6amMountain Time
In context
What each side covers.
Japan Standard Time
9:27amJST · UTC+09:00
Mountain Time
6:27pmMDT · UTC-06:00
Cities on this clock
Related converters
Other popular pairs.
Pacific Time
5:27pm
India Standard Time
5:57am
Pacific Time to India12 hours 30 minutes behind
Eastern Daylight Time
8:27pm
Central European Time
2:27am
Eastern Time to Central Europe6 hours behind
India Standard Time
5:57am
Eastern Daylight Time
8:27pm
India to Eastern Time9 hours 30 minutes ahead
British Summer Time
1:27am
India Standard Time
5:57am
London to India4 hours 30 minutes behind
Pacific Daylight Time
5:27pm
Eastern Daylight Time
8:27pm
Pacific to Eastern Time3 hours behind
Central European Time
2:27am
India Standard Time
5:57am
Central Europe to India3 hours 30 minutes behind
Frequently asked
Quick answers about converting between Japan Standard Time and Mountain Time. Can't find what you need? Email [email protected].
- What is the time difference between Japan Standard Time and Mountain Time?
- Japan Standard Time is 15 hours ahead of Mountain 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 9am in Japan Standard Time, what time is it in Mountain Time?
- 9am in Japan Standard Time is 6pm in Mountain Time on the previous day. Use the hour-by-hour table above to read any other time across — find the row and read the matching cell in the other column.
- What's the best time for a call between Japan Standard Time and Mountain Time?
- There's no comfortable 9-to-5 overlap between Japan Standard Time and Mountain Time — they sit on opposite sides of the planet's working day. Plan for an early or late call on one side, or hand work off asynchronously.
- Does this account for daylight saving time?
- Yes. We track every clock change in both places, so the abbreviations you see — JST 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.