12am in Guam is 11pm in Japan Standard Time on the previous day.

Frequently asked

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

What is the time difference between Guam and Japan Standard Time?

Guam is 1 hour ahead of Japan 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 12am in Guam, what time is it in Japan Standard Time?

12am in Guam is 11pm in Japan Standard Time on the previous day. It lands deep outside working hours in Japan Standard Time — see the best time to meet below for a friendlier slot. Use the hour-by-hour table above to read any other time across.

What's the best time for a call between Guam and Japan Standard Time?

10am–5pm in Guam lines up with 9am–4pm in Japan Standard Time — both sides are inside a 9-to-5 working day.

Does this account for daylight saving time?

Yes. We track every clock change in both places, so the abbreviations you see — ChST and JST — 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.