The short answer
Japan Standard Time is 15 hours ahead of Mountain Daylight Time.
Japan Standard Time☀
10:02:22am
JST · UTC+09:00 · Tue, Jul 21
Mountain Daylight Time☾
7:02:22pm
MDT · UTC-06:00 · Mon, Jul 20
Read across to convert
Japan Standard Time
JST · UTC+09:00
Mountain Daylight Time
MDT · UTC-06:00
Click any row to pin that hour across both zones.
12amTue
9amMon ·−1d
WORK1am
10amMon ·−1d
WORK2am
11amMon ·−1d
WORK3am
12pmMon ·−1d
WORK4am
1pmMon ·−1d
WORK5am
2pmMon ·−1d
WORK6am
3pmMon ·−1d
WORK7am
4pmMon ·−1d
WORK8am
5pmMon ·−1d
9am
WORK6pmMon ·−1d
NOW
10am
WORK7pmMon ·−1d
11am
WORK8pmMon ·−1d
12pm
WORK9pmMon ·−1d
1pm
WORK10pmMon ·−1d
2pm
WORK11pmMon ·−1d
3pm
WORK12amTue
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 Daylight Time
4pm–7pm
previous day
Popular conversions
Quick reference.
9amJapan Standard Time=6pmMountain Daylight Time · prev day
12pmJapan Standard Time=9pmMountain Daylight Time · prev day
3pmJapan Standard Time=12amMountain Daylight Time
5pmJapan Standard Time=2amMountain Daylight Time
9pmJapan Standard Time=6amMountain Daylight Time
In context
What each side covers.
Japan Standard Time
10:02amJST · UTC+09:00
Mountain Daylight Time
7:02pmMDT · UTC-06:00
Cities on this clock
Related converters
Other popular pairs.
Pacific Time
6:02pm
India Standard Time
6:32am
Pacific Time to India12 hours 30 minutes behind
Eastern Daylight Time
9:02pm
Central European Time
3:02am
Eastern Time to Central Europe6 hours behind
India Standard Time
6:32am
Eastern Daylight Time
9:02pm
India to Eastern Time9 hours 30 minutes ahead
British Summer Time
2:02am
India Standard Time
6:32am
London to India4 hours 30 minutes behind
Pacific Daylight Time
6:02pm
Eastern Daylight Time
9:02pm
Pacific to Eastern Time3 hours behind
Central European Time
3:02am
India Standard Time
6:32am
Central Europe to India3 hours 30 minutes behind
Frequently asked
Quick answers about converting between Japan Standard Time and Mountain Daylight Time. Can't find what you need? Email [email protected].
- What is the time difference between Japan Standard Time and Mountain Daylight Time?
- Japan Standard Time is 15 hours ahead of Mountain Daylight 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 Daylight Time?
- 9am in Japan Standard Time is 6pm in Mountain Daylight 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 Daylight Time?
- There's no comfortable 9-to-5 overlap between Japan Standard Time and Mountain Daylight 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.