JST to MST Converter
Mountain Time is on daylight saving time: MDT (UTC−6) until Sun, Nov 1.
Arizona stays on MST (UTC−7).
Start by searching for a time zone, city, or town.
Add one or more places to compare local times, adjust the date, and share the result.
Quick answers
Selected conversion
9:00 pm21:00 JST (UTC+9), Oct 18, 2026 = 6:00 am06:00 MDT (UTC-6), Oct 18, 2026
JST is 15 hours ahead of MDT.
JST and MST examples
These examples always use JST (UTC+9) and MST (UTC-7). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.
JST is 16 hours ahead of MST.
Most of Arizona stays on MST (UTC-7) all year. Places such as Denver use MDT (UTC-6) during daylight saving time, one hour later. For daylight-time examples, use JST to MDT.
How the time difference changes
For most of the year, JST is 15 hours ahead of MDT. From Nov 1, 2026 to Mar 14, 2027, JST is 16 hours ahead of MST.
For most of the year, working hours of 9:00 am to 6:00 pm in JST correspond to 6:00 pm (previous day) to 3:00 am in MDT. At other times of the year, working hours of 9:00 am to 6:00 pm in JST correspond to 5:00 pm (previous day) to 2:00 am in MST.For most of the year, working hours of 09:00 to 18:00 in JST correspond to 18:00 (previous day) to 03:00 in MDT. At other times of the year, working hours of 09:00 to 18:00 in JST correspond to 17:00 (previous day) to 02:00 in MST.
Compare JST time with MST time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.
Time Difference
Japan Standard Time is 15 hours ahead of Mountain Daylight Time.
9:00 pm21:00 in JST is 6:00 am06:00 in MDT
JST to MDT call time
Best time for a conference call or a meeting is between 8:30am-9:30am08:30-09:30 in JST which corresponds to 5:30pm-6:30pm17:30-18:30 in MDT (previous day). Their 9am–6pm09:00–18:00 working hours do not overlap; this is a suggested compromise.
9:00 pm21:00 Japan Standard Time (JST). Offset UTC +9:00 hours
6:00 am06:00 Mountain Daylight Time (MDT). Offset UTC -6:00 hours
9:00 pm21:00 JST / 6:00 am06:00 MDT
Choose an hour to update the converter. Day labels such as “next day” or “+1” are relative to the selected date in the first column. Use Up and Down arrow keys, Home or End to move between hours, then Enter or Space to select.
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Japan Standard Time
Offset: JST is 9 hours ahead of Greenwich Mean Time (GMT).
Countries using this time zone: Japan
Principal Cities: The largest city in the JST time zone is Tokyo in Japan, with about 9.733 million people. Other major cities in this time zone include Yokohama, Osaka, Nagoya, Sapporo.
Daylight Saving: Clocks in Japan Standard Time (JST) do not change for daylight saving time, so JST stays the same throughout the year. Other time zones may set clocks forward in summer and back in winter; see upcoming clock changes worldwide.
Current time in Japan: Japan time now
JST representations, usage and related time zones
- +09 - basic short
- +0900 - basic
- +09:00 - extended
- +0900 - sign character (+) followed by a four digit time providing hours (09) and minutes (00) of the offset. Indicates an offset of nine hours to the east of the zero meridian.
- India - Military abbreviation for JST
- I - short form of 'India'
- Asia/Tokyo
- Japan
- AWDT - Australian Western Daylight Time
- CHOST - Choibalsan Summer Time
- I - India Time Zone
- IRKST - Irkutsk Summer Time
- JST - Japan Standard Time
- KST - Korea Standard Time
- PWT - Palau Time
- TLT - East Timor Time
- ULAST - Ulaanbaatar Summer Time
- WIT - Eastern Indonesian Time
- YAKT - Yakutsk Time
Mountain Standard Time
Offset: MST is 7 hours behind Greenwich Mean Time (GMT).
Countries using this time zone: Canada, Mexico, United States
Principal Cities: The largest city in the MST time zone is Phoenix in the United States, with about 1.65 million people. Other major cities in this time zone include Ciudad Juárez, Hermosillo, Culiacán, Denver.
French: HNR - Heure Normale des Rocheuses
Spanish: MT - Zona Pacífico
Today the lighter areas are on UTC−6 (MDT).
Daylight Saving: This is a standard time zone. During summer, some places set clocks forward one hour for daylight saving time and observe Mountain Daylight Time (MDT).
End: Mountain Standard Time (MST) ended on Sunday, March 8, 2026 at 2:00 am02:00 local time and clocks were set one hour forward to Sunday, March 8, 2026, 3:00 am03:00 local daylight time instead. Standard time ends annually on the second Sunday of March.
Start: Mountain Standard Time (MST) starts on Sunday, November 1, 2026 at 2:00 am02:00 local time and clocks are set one hour back to Sunday, November 1, 2026, 1:00 am01:00. Standard time starts annually on the first Sunday of November.
See USA daylight saving time and upcoming clock changes worldwide.
MST representations, usage and related time zones
- -07 - basic short
- -0700 - basic
- -07:00 - extended
- -0700 - sign character (-) followed by a four digit time providing hours (07) and minutes (00) of the offset. Indicates an offset of seven hours to the west of the zero meridian.
- Tango - Military abbreviation for MST
- T - short form of 'Tango'
- America/Boise
- America/Cambridge_Bay
- America/Ciudad_Juarez
- America/Creston
- America/Dawson
- America/Dawson_Creek
- America/Denver
- America/Edmonton
- America/Fort_Nelson
- America/Hermosillo
- America/Inuvik
- America/Mazatlan
- America/Phoenix
- America/Shiprock
- America/Whitehorse
- America/Yellowknife
- Canada/Mountain
- Canada/Yukon
- MST
- MST7MDT
- Mexico/BajaSur
- Navajo
- US/Arizona
- US/Mountain
- MST - Mountain Standard Time
- PDT - Pacific Daylight Time
- YST - Yukon Standard Time
- T - Tango Time Zone