8am in Tokyo is 5pm in Mountain Standard Time on the previous day.

Frequently asked

Quick answers about converting between Tokyo and Mountain Standard Time. Can't find what you need? Email [email protected].

What is the time difference between Tokyo and Mountain Standard Time?

Tokyo is 15 hours ahead of Mountain Standard 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 8am in Tokyo, what time is it in Mountain Standard Time?

8am in Tokyo is 5pm in Mountain Standard Time on the previous day. That's already evening in Mountain Standard Time, after the typical working day ends. Use the hour-by-hour table above to read any other time across.

What's the best time for a call between Tokyo and Mountain Standard Time?

There's no comfortable 9-to-5 overlap between Tokyo and Mountain Standard 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.