The short answer

12am in Chatham Standard Time is 12:15pm in Greenwich Mean Time on the previous day.

Chatham Standard Time is 11 hours 45 minutes ahead of Greenwich Mean Time. It falls outside the 9-to-5 in Chatham Standard Time but lands inside working hours in Greenwich Mean Time.

Chatham Standard Time☾
12am
Greenwich Mean Time☀
12:15pm
previous day
Right now
10:27am+12:45 · UTC+12:45 · Thu, Jun 25
10:42pmBST · UTC+01:00 · Wed, Jun 24
Read across to convert
Chatham Standard Time
+12:45 · UTC+12:45
10:27am ☀
Greenwich Mean Time
BST · UTC+01:00
10:42pm ☾
Pinned12amChatham Standard Time=12:15pmGreenwich Mean Time · Wed (previous day)
PINNED
12amThu
12:15pmWed ·−1d
WORK
1am
1:15pmWed ·−1d
WORK
2am
2:15pmWed ·−1d
WORK
3am
3:15pmWed ·−1d
WORK
4am
4:15pmWed ·−1d
WORK
5am
5:15pmWed ·−1d
6am
6:15pmWed ·−1d
7am
7:15pmWed ·−1d
8am
8:15pmWed ·−1d
9am
WORK
9:15pmWed ·−1d
NOW
10am
WORK
10:15pmWed ·−1d
11am
WORK
11:15pmWed ·−1d
12pm
WORK
12:15amThu
1pm
WORK
1:15am
2pm
WORK
2:15am
3pm
WORK
3:15am
4pm
WORK
4:15am
5pm
5:15am
6pm
6:15am
7pm
7:15am
8pm
8:15am
9pm
9:15am
WORK
10pm
10:15am
WORK
11pm
11:15am
WORK
daylightnightworking hoursoverlap
Convert a specific time12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
Best time to meet
No shared working hours.

Chatham Standard Time and Greenwich Mean Time are too far apart for a working-day overlap. The least-unsociable option is an early-morning call on one side and an evening one on the other — or hand work off asynchronously and let the planet do the waiting.

Popular conversions

Quick reference.

9amChatham Standard Time=9:15pmGreenwich Mean Time · prev day
12pmChatham Standard Time=12:15amGreenwich Mean Time
3pmChatham Standard Time=3:15amGreenwich Mean Time
5pmChatham Standard Time=5:15amGreenwich Mean Time
9pmChatham Standard Time=9:15amGreenwich Mean Time
In context

What each side covers.

Chatham Standard Time
+12:45 · UTC+12:45
10:27am

Chatham Standard Time

Greenwich Mean Time
BST · UTC+01:00
10:42pm
Cities on this clock
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Frequently asked

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

What is the time difference between Chatham Standard Time and Greenwich Mean Time?
Chatham Standard Time is 11 hours 45 minutes ahead of Greenwich Mean 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 Chatham Standard Time, what time is it in Greenwich Mean Time?
12am in Chatham Standard Time is 12:15pm in Greenwich Mean Time on the previous day. It falls outside the 9-to-5 in Chatham Standard Time but lands inside working hours in Greenwich Mean Time. Use the hour-by-hour table above to read any other time across.
What's the best time for a call between Chatham Standard Time and Greenwich Mean Time?
There's no comfortable 9-to-5 overlap between Chatham Standard Time and Greenwich Mean 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 — +12:45 and BST — 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.