JST to MST
On Oct 23, 2026, Mountain Time is 15 hours behind Japan Standard Time: 9:00 AM JST is 6:00 PM MDT the previous day. The gap changes during the year because of daylight saving time; the dates are below.
MST vs JST over the next 12 months
| Period | MST is | Example |
|---|---|---|
| Oct 23, 2026 to Nov 1, 2026 | 15 hours behind | 9:00 AM JST = 6:00 PM MDT (previous day) |
| Nov 1, 2026 to Mar 14, 2027 | 16 hours behind | 9:00 AM JST = 5:00 PM MST (previous day) |
| Mar 14, 2027 onwards | 15 hours behind | 9:00 AM JST = 6:00 PM MDT (previous day) |
JST to MST conversion table
Every hour of a weekday around Oct 23, 2026, in both zones.
| Japan Standard Time | Mountain Time |
|---|---|
| 12:00 AM | 9:00 AM (previous day) |
| 1:00 AM | 10:00 AM (previous day) |
| 2:00 AM | 11:00 AM (previous day) |
| 3:00 AM | 12:00 PM (previous day) |
| 4:00 AM | 1:00 PM (previous day) |
| 5:00 AM | 2:00 PM (previous day) |
| 6:00 AM | 3:00 PM (previous day) |
| 7:00 AM | 4:00 PM (previous day) |
| 8:00 AM | 5:00 PM (previous day) |
| 9:00 AM | 6:00 PM (previous day) |
| 10:00 AM | 7:00 PM (previous day) |
| 11:00 AM | 8:00 PM (previous day) |
| 12:00 PM | 9:00 PM (previous day) |
| 1:00 PM | 10:00 PM (previous day) |
| 2:00 PM | 11:00 PM (previous day) |
| 3:00 PM | 12:00 AM |
| 4:00 PM | 1:00 AM |
| 5:00 PM | 2:00 AM |
| 6:00 PM | 3:00 AM |
| 7:00 PM | 4:00 AM |
| 8:00 PM | 5:00 AM |
| 9:00 PM | 6:00 AM |
| 10:00 PM | 7:00 AM |
| 11:00 PM | 8:00 AM |
Best time for a meeting
There is no 9-to-5 overlap; within an 8 AM–8 PM day the zones overlap for 3 hours on a weekday: 8:00 AM–11:00 AM JST, which is 5:00 PM–8:00 PM MDT.
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Daylight saving time
Mountain Time (MST/MDT)
- Nov 1, 2026: clocks go back 1 hour at 2:00 AM (UTC−6 → UTC−7)
- Mar 14, 2027: clocks go forward 1 hour at 2:00 AM (UTC−7 → UTC−6)
Where these clocks are used
- Japan Standard Time (JST): all of Japan. IANA zone
Asia/Tokyo. - Mountain Time (MST/MDT): Denver, Salt Lake City, Calgary. IANA zone
America/Denver.
Questions
What time is it in MST when it is 9 AM JST?
On Oct 23, 2026, 9:00 AM JST is 6:00 PM MDT the previous day. On other dates the answer can shift by an hour because of daylight saving time; the table of periods on this page gives each one.
How many hours behind JST is MST?
It depends on the date. Oct 23, 2026 to Nov 1, 2026: MST is 15 hours behind. Nov 1, 2026 to Mar 14, 2027: MST is 16 hours behind. Mar 14, 2027 onwards: MST is 15 hours behind.
Do JST and MST observe daylight saving time?
Japan Standard Time stays on UTC+9 all year. Mountain Time switches to MDT (UTC−6) in summer and back to MST (UTC−7) in winter.
What is the best time for a meeting between JST and MST?
There is no 9-to-5 overlap; within an 8 AM–8 PM day the zones overlap for 3 hours on a weekday: 8:00 AM–11:00 AM JST, which is 5:00 PM–8:00 PM MDT.
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Related conversions
- MST to JST (reverse)
- EST to MST
- CST to MST
- PST to MST
- UTC to MST
- GMT to MST
- CET to MST
- IST to MST
- SGT to MST
- JST to EST
- JST to CST
- JST to PST
- All time zones
Computed from the IANA time zone database on Oct 23, 2026. Live clocks and the converter use your browser's copy of the same data.