The short answer

Cook Islands Standard Time is 19 hours behind Japan Standard Time.

Cook Islands Standard Time
4:21:27pm
-10:00 · UTC-10:00 · Tue, Jun 23
Japan Standard Time
11:21:27am
JST · UTC+09:00 · Wed, Jun 24
Read across to convert
Cook Islands Standard Time
-10:00 · UTC-10:00
4:21pm ☀
Japan Standard Time
JST · UTC+09:00
11:21am ☀
Click any row to pin that hour across both zones.
12amTue
7pm
1am
8pm
2am
9pm
3am
10pm
4am
11pm
5am
12amWed ·+1d
6am
1amWed ·+1d
7am
2amWed ·+1d
8am
3amWed ·+1d
9am
WORK
4amWed ·+1d
10am
WORK
5amWed ·+1d
11am
WORK
6amWed ·+1d
12pm
WORK
7amWed ·+1d
1pm
WORK
8amWed ·+1d
2pm
WORK
9amWed ·+1d
WORK
3pm
WORK
10amWed ·+1d
WORK
NOW
4pm
WORK
11amWed ·+1d
WORK
5pm
12pmWed ·+1d
WORK
6pm
1pmWed ·+1d
WORK
7pm
2pmWed ·+1d
WORK
8pm
3pmWed ·+1d
WORK
9pm
4pmWed ·+1d
WORK
10pm
5pmWed ·+1d
11pm
6pmWed ·+1d
daylightnightworking hoursoverlap
Best time to meet
Best for a call
Cook Islands Standard Time
2pm–5pm
=
Japan Standard Time
9am–12pm
next day
Popular conversions

Quick reference.

9amCook Islands Standard Time=4amJapan Standard Time · next day
12pmCook Islands Standard Time=7amJapan Standard Time · next day
3pmCook Islands Standard Time=10amJapan Standard Time · next day
5pmCook Islands Standard Time=12pmJapan Standard Time · next day
9pmCook Islands Standard Time=4pmJapan Standard Time · next day
In context

What each side covers.

Cook Islands Standard Time
-10:00 · UTC-10:00
4:21pm
Cities on this clock
Japan Standard Time
JST · UTC+09:00
11:21am
Cities on this clock

Frequently asked

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

What is the time difference between Cook Islands Standard Time and Japan Standard Time?
Cook Islands Standard Time is 19 hours behind 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 9am in Cook Islands Standard Time, what time is it in Japan Standard Time?
9am in Cook Islands Standard Time is 4am in Japan Standard Time on the next day. Use the hour-by-hour table above to read any other time across — find the row and read the matching cell in the other column.
What's the best time for a call between Cook Islands Standard Time and Japan Standard Time?
2pm–5pm in Cook Islands Standard Time lines up with 9am–12pm in Japan Standard Time the next day — 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 — -10:00 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.