Date/Time Types

Postgres supports the full set of SQL date and time types.

Table 3-7. Postgres Date/Time Types

timestampboth date and time8 bytes4713 BCAD 14650011 microsec / 14 digits
timestamp with time zonedate and time with time zone8 bytes1903 AD2037 AD1 microsec / 14 digits
intervalfor time intervals12 bytes-178000000 years178000000 years1 mircosecond
datedates only4 bytes4713 BC32767 AD1 day
timetimes of day only4 bytes00:00:00.0023:59:59.991 microsecond
time with time zonetimes of day only4 bytes00:00:00.00+1223:59:59.99-121 microsecond

Note: To ensure compatibility to earlier versions of Postgres we also continue to provide datetime (equivalent to timestamp) and timespan (equivalent to interval), however support for these is now restricted to having an implicit translation to timestamp and interval. The types abstime and reltime are lower precision types which are used internally. You are discouraged from using any of these types in new applications and are encouraged to move any old ones over when appropriate. Any or all of these internal types might disappear in a future release.

Date/Time Input

Date and time input is accepted in almost any reasonable format, including ISO-8601, SQL-compatible, traditional Postgres, and others. The ordering of month and day in date input can be ambiguous, therefore a setting exists to specify how it should be interpreted in ambiguous cases. The command SET DateStyle TO 'US' or SET DateStyle TO 'NonEuropean' specifies the variant "month before day", the command SET DateStyle TO 'European' sets the variant "day before month". The ISO style is the default but this default can be changed at compile time or at run time.

See Date/Time Support for the exact parsing rules of date/time input and for the recognized time zones.

Remember that any date or time input needs to be enclosed into single quotes, like text strings.


The following are possible inputs for the date type.

Table 3-8. Postgres Date Input

January 8, 1999Unambiguous
1999-01-08ISO-8601 format, preferred
1/8/1999US; read as August 1 in European mode
8/1/1999European; read as August 1 in US mode
1/18/1999US; read as January 18 in any mode
19990108ISO-8601 year, month, day
990108ISO-8601 year, month, day
1999.008Year and day of year
99008Year and day of year
January 8, 99 BCYear 99 before the Common Era

Table 3-9. Postgres Month Abbreviations

SeptemberSep, Sept

Note: The month May has no explicit abbreviation, for obvious reasons.

Table 3-10. Postgres Day of Week Abbreviations

TuesdayTue, Tues
WednesdayWed, Weds
ThursdayThu, Thur, Thurs


The following are valid time inputs.

Table 3-11. Postgres Time Input

04:05 AMSame as 04:05; AM does not affect value
04:05 PMSame as 16:05; input hour must be <= 12
zSame as 00:00:00
zuluSame as 00:00:00
allballsSame as 00:00:00

time with time zone

This type is defined by SQL92, but the definition exhibits fundamental deficiencies which renders the type nearly useless. In most cases, a combination of date, time, and timestamp should provide a complete range of date/time functionality required by any application.

time with time zone accepts all input also legal for the time type, appended with a legal time zone, as follows:

Table 3-12. Postgres Time With Time Zone Input


Refer to Postgres Time Zone Input for more examples of time zones.


Valid input for the timestamp type consists of a concatenation of a date and a time, followed by an optional AD or BC, followed by an optional time zone. (See below.) Thus

1999-01-08 04:05:06 -8:00
is a valid timestamp value, which is ISO-compliant. In addition, the wide-spread format
January 8 04:05:06 1999 PST
is supported.

Table 3-13. Postgres Time Zone Input

Time ZoneDescription
PSTPacific Standard Time
-8:00ISO-8601 offset for PST
-800ISO-8601 offset for PST
-8ISO-8601 offset for PST


intervals can be specified with the following syntax:

  Quantity Unit [Quantity Unit...] [Direction]
@ Quantity Unit [Direction]
where: Quantity is ..., -1, 0, 1, 2, ...; Unit is second, minute, hour, day, week, month, year, decade, century, millennium, or abbreviations or plurals of these units; Direction can be ago or empty.

Special values

The following SQL-compatible functions can be used as date or time input for the corresponding datatype: CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP.

Postgres also supports several special constants for convenience.

Table 3-14. Postgres Special Date/Time Constants

currentCurrent transaction time, deferred
epoch1970-01-01 00:00:00+00 (Unix system time zero)
infinityLater than other valid times
-infinityEarlier than other valid times
invalidIllegal entry
nowCurrent transaction time
todayMidnight today
tomorrowMidnight tomorrow
yesterdayMidnight yesterday
'now' is resolved when the value is inserted, 'current' is resolved everytime the value is retrieved. So you probably want to use 'now' in most applications. (Of course you really want to use CURRENT_TIMESTAMP, which is equivalent to 'now'.)

Date/Time Output

Output formats can be set to one of the four styles ISO-8601, SQL (Ingres), traditional Postgres, and German, using the SET DateStyle. The default is the ISO format.

Table 3-15. Postgres Date/Time Output Styles

Style SpecificationDescriptionExample
'ISO'ISO-8601 standard1997-12-17 07:37:16-08
'SQL'Traditional style12/17/1997 07:37:16.00 PST
'Postgres'Original styleWed Dec 17 07:37:16 1997 PST
'German'Regional style17.12.1997 07:37:16.00 PST

The output of the date and time styles is of course only the date or time part in accordance with the above examples.

The SQL style has European and non-European (US) variants, which determines whether month follows day or vica versa. (See also above at Date/Time Input, how this setting affects interpretation of input values.)

Table 3-16. Postgres Date Order Conventions

Style SpecificationDescriptionExample
Europeanday/month/year17/12/1997 15:37:16.00 MET
USmonth/day/year12/17/1997 07:37:16.00 PST

interval output looks like the input format, except that units like week or century are converted to years and days. In ISO mode the output looks like

[ Quantity Units [ ... ] ] [ Days ] Hours:Minutes [ ago ]

There are several ways to affect the appearance of date/time types:

Time Zones

Postgres endeavors to be compatible with SQL92 definitions for typical usage. However, the SQL92 standard has an odd mix of date and time types and capabilities. Two obvious problems are:

Time zones in the real world can have no meaning unless associated with a date as well as a time since the offset may vary through the year with daylight savings time boundaries.

To address these difficulties, Postgres associates time zones only with date and time types which contain both date and time, and assumes local time for any type containing only date or time. Further, time zone support is derived from the underlying operating system time zone capabilities, and hence can handle daylight savings time and other expected behavior.

Postgres obtains time zone support from the underlying operating system for dates between 1902 and 2038 (near the typical date limits for Unix-style systems). Outside of this range, all dates are assumed to be specified and used in Universal Coordinated Time (UTC).

All dates and times are stored internally in Universal UTC, alternately known as Greenwich Mean Time (GMT). Times are converted to local time on the database server before being sent to the client frontend, hence by default are in the server time zone.

There are several ways to affect the time zone behavior:

If an invalid time zone is specified, the time zone becomes GMT (on most systems anyway).

Note: If the compiler option USE_AUSTRALIAN_RULES is set then EST refers to Australia Eastern Std Time, which has an offset of +10:00 hours from UTC.


Postgres uses Julian dates for all date/time calculations. They have the nice property of correctly predicting/calculating any date more recent than 4713BC to far into the future, using the assumption that the length of the year is 365.2425 days.

Date conventions before the 19th century make for interesting reading, but are not consistant enough to warrant coding into a date/time handler.