JST to MST
-16hJST
JSTSOURCEMST
MSTGreen rows indicate typical business hours (9 AM - 5 PM)
JST and MST on the World Map
The map below highlights the JST (Japan Standard Time) and MST (Mountain Standard Time) timezone regions across the globe.
JST – Japan Standard Time
UTC+09:00Japan Standard Time (JST) is the time zone for Japan, 9 hours ahead of UTC.
- •Japan does not observe daylight saving time.
- •Tokyo is the most populous metropolitan area in the world.
- •The Tokyo Stock Exchange operates from 9:00 AM to 3:00 PM JST.
- •JST is 14 hours ahead of EST and 9 hours ahead of GMT.
MST – Mountain Standard Time
UTC-07:00Mountain Standard Time (MST) is the time zone for the Mountain region of North America, 7 hours behind UTC.
- •Arizona does not observe daylight saving time, staying on MST year-round.
- •The Navajo Nation in Arizona does observe DST, unlike the rest of the state.
- •Denver, the 'Mile High City', is the largest city fully in MST.
- •MST covers 6 US states entirely and parts of several others.
Comparing Time Zones: JST and MST
JST runs on Japan Standard Time (JST) at UTC+09:00. MST runs on Mountain Standard Time (MST) at UTC-07:00. That puts JST 16 hours behind MST — a difference of -16h at the current offsets.
In practice, when it is 9:00 AM in JST it is 5:00 PM in MST on the previous day. Midnight in JST is 8:00 AM in MST. Neither zone observes daylight saving time, so the offset between them stays constant all year.
JST to MST time conversion table
| JST (JST) | MST (MST) | Day |
|---|---|---|
| 12:00 AM | 8:00 AM | previous day |
| 6:00 AM | 2:00 PM | previous day |
| 7:00 AM | 3:00 PM | previous day |
| 8:00 AM | 4:00 PM | previous day |
| 9:00 AM | 5:00 PM | previous day |
| 12:00 PM | 8:00 PM | previous day |
| 3:00 PM | 11:00 PM | previous day |
| 5:00 PM | 1:00 AM | same day |
| 6:00 PM | 2:00 AM | same day |
| 9:00 PM | 5:00 AM | same day |
Why people convert JST to MST time
- Scheduling a call from JST to MST: a 10:00 AM start in JST lands at 6:00 PM in MST the previous day, so you can confirm the slot without doing the arithmetic yourself.
- Handling a -16h gap: JST and MST have no overlap inside a normal 9-to-5 day, so real-time meetings need an early-morning or late-evening slot on one side. 9:00 AM in MST is 5:00 PM in JST.
- Watching a live event or market open: JST viewers need 5:00 PM in MST to catch a 9:00 AM start there, and 4:00 PM if the event is anchored to JST.
- Always state the zone abbreviation, not just the hour. "3:00 PM JST" is unambiguous; "3 PM" across a -16h gap is not.
- With a -16h gap there is no shared 9-to-5 window, so alternate the early start: one week JST takes the early slot, the next week MST does.
About JST (Japan Standard Time)
Japan Standard Time (JST) is the standard time zone for all of Japan. Japan does not observe daylight saving time. JST is 9 hours ahead of UTC and 14 hours ahead of EST. The Tokyo Stock Exchange, the world's third largest by market capitalization, operates on JST. South Korea uses the same offset (KST) but it is a distinct time zone.
About MST (Mountain Standard Time)
Mountain Standard Time (MST) covers the Rocky Mountain region of the United States and Canada. Arizona is notable for not observing daylight saving time, staying on MST year-round (except the Navajo Nation). The time zone includes major cities like Denver, Phoenix, Calgary, and Salt Lake City. During summer, most areas switch to Mountain Daylight Time (MDT, UTC-06:00).
Best time to call between JST and MST
With a -16h offset there is no overlap inside a normal 9 AM – 5 PM day. MST opens at 9:00 AM MST, which is 5:00 PM in JST, so real-time calls need an early-morning or late-evening slot on one side.
Business hours overlap
JST and MST have no shared working hours because of the -16h gap. Teams need to alternate early starts or rely on asynchronous handovers.
JST is 16 hours behind MST (JST UTC+09:00 → MST UTC-07:00). There is no shared 9-to-5 window, so plan around an early or late slot. Remember to re-check around daylight-saving transitions.
🕐 Daylight Saving Time Info
JST
Does not observe DST
MST
☀ Currently in DST
Standard: UTC-07:00 · DST: UTC-06:00
Clocks fall back on Sun, Nov 1, 2026
Learn More About Time
Dive deeper into the fascinating world of timekeeping, time zones, and how they shape our global society:
Frequently Asked Questions
What is the time difference between JST and MST?
JST (JST, UTC+09:00) is 16 hours behind MST (MST, UTC-07:00). The gap is currently -16h.
How do I convert JST time to MST time?
Add -16h to JST local time. For example, 9:00 AM in JST is 5:00 PM in MST (previous day).
What time is it in MST right now?
MST uses MST at UTC-07:00. Use the live converter at the top of this page — it updates in real time and already accounts for the -16h offset from JST.
What is the best time to call MST from JST?
There is no shared working-hours window because of the -16h gap. The closest option is 1:00 PM in JST, which is 9:00 PM in MST.
Which is behind, JST or MST?
JST is 16 hours behind MST. When it is 12:00 PM in JST it is 8:00 PM in MST.
Does daylight saving time affect the JST–MST difference?
Neither zone observes daylight saving time, so the -16h offset between JST and MST is fixed all year.
Which other cities share JST's time zone?
JST also covers Tokyo, Osaka, Yokohama, Nagoya, Sapporo, Kyoto, Kobe, Fukuoka and 1 more.
Which countries use JST, JST's zone?
JST is used in Japan.
Is there a day difference between JST and MST?
Sometimes. The -16h gap is large enough that 8:00 PM or later in JST already falls on the in MST.
What is the time difference between JST and MST?
MST is -16h from JST.
What timezone is JST in?
JST operates on its local timezone.
What timezone is MST in?
MST operates on its local timezone.
Which countries use JST (Japan Standard Time)?
JST is used in Japan.
Does JST observe daylight saving time?
No, JST does not observe daylight saving time and remains at UTC+09:00 year-round.
What are some interesting facts about JST?
Japan does not observe daylight saving time. Tokyo is the most populous metropolitan area in the world.
Which cities are in the MST timezone?
Major cities in the MST timezone include Denver, Phoenix, Salt Lake City, Calgary, Edmonton, Albuquerque, El Paso, Tucson.
What is the UTC offset for MST?
Mountain Standard Time (MST) is at UTC-07:00. During daylight saving time, it shifts to MDT.
What should I know about the MST timezone?
Arizona does not observe daylight saving time, staying on MST year-round. The Navajo Nation in Arizona does observe DST, unlike the rest of the state.
When is it midnight in JST, what time is it in MST?
When it is 12:00 AM (midnight) in JST (JST), it is -16h later in MST (MST).
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