The Chatham Standard Time Zone is a time zone twelve hours and forty-five minutes ahead of Coordinated Universal Time (UTC) resulting in UTC+12:45. It is used exclusively in the Chatham Islands, New Zealand. It is one of three time zones with a 45-minute offset from UTC, the others being Nepal Standard Time (UTC+05:45) and the unofficial Australian Central Western Time (UTC+08:45).

During summer, daylight saving time is observed and clocks are advanced one hour. Chatham Daylight Time (CHADT) is 13 hours 45 minutes ahead of UTC, 45 minutes ahead of New Zealand Daylight Time (NZDT). Daylight saving time runs from the last Sunday in September at 2:45 to the first Sunday in April at 3:45.

43°53′54″S 176°31′44″W / 43.89833°S 176.52889°W / -43.89833; -176.52889