JST to MST Converter

Japan Standard Time → Mountain Standard Time · JST is 16 hours ahead of MST

JST
—
MST
—

JST and MST are the same time

JST to MST Conversion Table

JSTMST
12:00 AM12:00 AM
1:00 AM1:00 AM
2:00 AM2:00 AM
3:00 AM3:00 AM
4:00 AM4:00 AM
5:00 AM5:00 AM
6:00 AM6:00 AM
7:00 AM7:00 AM
8:00 AM8:00 AM
9:00 AM9:00 AM
10:00 AM10:00 AM
11:00 AM11:00 AM
12:00 PM12:00 PM
1:00 PM1:00 PM
2:00 PM2:00 PM
3:00 PM3:00 PM
4:00 PM4:00 PM
5:00 PM5:00 PM
6:00 PM6:00 PM
7:00 PM7:00 PM
8:00 PM8:00 PM
9:00 PM9:00 PM
10:00 PM10:00 PM
11:00 PM11:00 PM

Green rows = business hours overlap (9:00 AM – 6:00 PM JST)

Major JST Cities
  • Tokyo
  • Osaka
  • Kyoto
  • Yokohama
  • Sapporo
  • Fukuoka
Major MST Cities
  • Denver, CO
  • Salt Lake City, UT
  • Albuquerque, NM
  • Tucson, AZ
  • Boise, ID
  • El Paso, TX
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JST vs MST — Tokyo to Denver

JST (UTC+9) — Japan has no DST, always UTC+9. MST (UTC-7) — Mountain US shifts to MDT (UTC-6) in summer.

At 16 hours ahead, Tokyo is always on the next calendar day compared to Denver. The gap is among the largest for regular business pairs. Async-first workflows are essential for Japan–Mountain US collaboration.

Frequently Asked Questions

How many hours is JST ahead of MST?

JST (Japan Standard Time, UTC+9) is 16 hours ahead of MST (Mountain Standard Time, UTC-7). During US Mountain Daylight Time (MDT, UTC-6), JST is 15 hours ahead. Japan does not observe DST, so the gap only changes when the US shifts clocks in spring and autumn.

What is 9 AM JST in MST?

9:00 AM JST (Tokyo) is 5:00 PM MST the previous day. For example, Tuesday 9:00 AM Tokyo = Monday 5:00 PM Denver (in winter). During MDT (US summer), 9:00 AM JST = 6:00 PM MDT the previous day.

What is the best time to call Denver from Tokyo?

The best window to call Denver (MST) from Tokyo (JST) in winter is 4:00–8:00 PM JST = 12:00 AM–4:00 AM MST — which is impractical. In practice, Tokyo evening (8:00–10:00 PM JST) = Denver morning (4:00–6:00 AM MST) is the closest workable overlap. Async communication is standard for Japan–Mountain US teams.

What date is it in Denver when it is Monday in Tokyo?

With a 16-hour lead, Tokyo is always on the next calendar day compared to Denver. When it is Monday morning in Tokyo, it is still Sunday in Denver. A Tuesday meeting in Tokyo must be booked as a Monday in Denver.