A date and time library for Clojure, wrapping the Joda Time library.
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Latest commit a077193 Dec 30, 2016 @steveshogren steveshogren committed with seancorfield Clarify the README for today-at (#224)
* Additional clarification about which date

* Clarified today-at example


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A date and time library for Clojure, wrapping the Joda Time library.


clj-time artifacts are released to Clojars.

If you are using Maven, add the following repository definition to your pom.xml:


The Most Recent Release

With Leiningen:

[clj-time "0.13.0"]

With Maven:


Bugs and Enhancements

Please open issues against the official clj-time repo on Github.

Mailing List

Please ask questions on the clj-time mailing list.



The main namespace for date-time operations in the clj-time library is clj-time.core.

(require '[clj-time.core :as t])

Create a DateTime instance with date-time, specifying the year, month, day, hour, minute, second, and millisecond:

(t/date-time 1986 10 14 4 3 27 456)
=> #<DateTime 1986-10-14T04:03:27.456Z>

Less-significant fields can be omitted:

(t/date-time 1986 10 14)
=> #<DateTime 1986-10-14T00:00:00.000Z>

Get the current time with now and the start of the Unix epoch with epoch.

Once you have a date-time, use accessors like hour and second to access the corresponding fields:

(t/hour (t/date-time 1986 10 14 22))
=> 22

The date-time constructor always returns times in the UTC time zone. If you want a time with the specified fields in a different time zone, use from-time-zone:

(t/from-time-zone (t/date-time 1986 10 22) (t/time-zone-for-offset -2))
=> #<DateTime 1986-10-22T00:00:00.000-02:00>

If on the other hand you want a given absolute instant in time in a different time zone, use to-time-zone:

(t/to-time-zone (t/date-time 1986 10 22) (t/time-zone-for-offset -2))
=> #<DateTime 1986-10-21T22:00:00.000-02:00>

In addition to time-zone-for-offset, you can use the time-zone-for-id and default-time-zone functions and the utc Var to construct or get DateTimeZone instances.

If you only want a date with no time component, consider using the local-date and today functions. These return LocalDate instances that do not have time components (and thus don't suffer from timezone-related shifting).

(t/local-date 2013 3 20)
=> #<LocalDate 2013-03-20>

The functions equal?, after?, and before? determine the relative position of two DateTime instances:

(t/equal? (t/date-time 1986 10) (t/date-time 1986 10))
=> true
(t/after? (t/date-time 1986 10) (t/date-time 1986 9))
=> true
(t/before? (t/date-time 1986 9) (t/date-time 1986 10))
=> true

Often you will want to find a date some amount of time from a given date. For example, to find the time 1 month and 3 weeks from a given date-time:

(t/plus (t/date-time 1986 10 14) (t/months 1) (t/weeks 3))
=> #<DateTime 1986-12-05T00:00:00.000Z>

An Interval is used to represent the span of time between two DateTime instances. Construct one using interval, then query them using within?, overlaps?, and abuts?

(t/within? (t/interval (t/date-time 1986) (t/date-time 1990))
              (t/date-time 1987))
=> true

The in-seconds and in-minutes functions can be used to describe intervals in the corresponding temporal units:

(t/in-minutes (t/interval (t/date-time 1986 10 2) (t/date-time 1986 10 14)))
=> 17280

The overlap function can be used to get an Interval representing the overlap between two intervals:

(t/overlap (t/interval (t/date-time 1986) (t/date-time 1990))
         (t/interval (t/date-time 1987) (t/date-time 1991)))
=> #<Interval 1987-01-01T00:00:00.000Z/1990-01-01T00:00:00.000Z>

today-at returns a moment in time at the given hour, minute and second on the current date UTC; not the current system date:

(t/today-at 12 00)
=> #<DateTime 2013-03-29T12:00:00.000Z>
(t/today-at 12 00 05)
=> #<DateTime 2013-03-29T12:00:05.000Z>

;; System clock says 11PM on 12/20/2016 UTC-5
(t/today-at 7 00 00)
=> #<DateTime 2016-12-21T7:00:00.000Z>


If you need to parse or print date-times, use clj-time.format:

(require '[clj-time.format :as f])

Parsing and printing are controlled by formatters. You can either use one of the built in ISO8601 formatters or define your own, e.g.:

(def built-in-formatter (f/formatters :basic-date-time))
(def custom-formatter (f/formatter "yyyyMMdd"))

To see a list of available built-in formatters and an example of a date-time printed in their format:


Remember that mm is minutes, MM is months, ss is seconds and SS is milliseconds. You can find a complete list of patterns on the Joda Time website.

Once you have a formatter, parsing and printing are straightforward:

(f/parse custom-formatter "20100311")
=> #<DateTime 2010-03-11T00:00:00.000Z>
(f/unparse custom-formatter (t/date-time 2010 10 3))
=> "20101003"

To parse dates in multiple formats and format dates in just one format, you can do this:

(def multi-parser (f/formatter (t/default-time-zone) "YYYY-MM-dd" "YYYY/MM/dd"))

(f/unparse multi-parser (f/parse multi-parser "2012-02-01"))
=> "2012-02-01"

(f/unparse multi-parser (f/parse multi-parser "2012/02/01"))
=> "2012-02-01"


The namespace clj-time.coerce contains utility functions for coercing Joda DateTime instances to and from various other types:

(require '[clj-time.coerce :as c])

For example, to convert a Joda DateTime to and from a Java long:

(c/to-long (t/date-time 1998 4 25))
=> 893462400000
(c/from-long 893462400000)
=> #<DateTime 1998-04-25T00:00:00.000Z>

And by the magic of protocols you can pass in an isoformat string and get the unix epoch milliseconds:

(c/to-long "2013-08-01")
=> 1375315200000

There are also conversions to and from java.util.Date (to-date and from-date), java.sql.Date (to-sql-date and from-sql-date), java.sql.Timestamp (to-sql-time and from-sql-time) and several other types.


The namespace clj-time.local contains functions for working with local time without having to shift to/from utc, the preferred time zone of clj-time.core.

(require '[clj-time.local :as l])

Get the current local time with


Get a local date-time instance retaining the time fields with

(l/to-local-date-time obj)

The following all return 1986-10-14 04:03:27.246 with the local time zone.

(l/to-local-date-time (clj-time.core/date-time 1986 10 14 4 3 27 246))
(l/to-local-date-time "1986-10-14T04:03:27.246")
(l/to-local-date-time "1986-10-14T04:03:27.246Z")

The dynamic var *local-formatters* contains a map of local formatters for parsing and printing. It is initialized with all the formatters in clj-time.format localized.

to-local-date-time for strings uses *local-formatters* to parse.

Format an obj using a formatter in *local-formatters* corresponding to the format-key passed in with

(l/format-local-time (l/local-now) :basic-date-time)


clj-time.periodic/periodic-seq returns an infinite sequence of instants separated by a time period starting with the given point in time:

(require '[clj-time.periodic :as p])
(require '[clj-time.core :as t])

;; returns 10 instants starting with current time separated
;; by 12 hours
(take 10 (p/periodic-seq (t/now) (t/hours 12)))

In particular, if you ask for a sequence of instants separated by a month, you will get dates where the month increases each time (rather than being, say, 30 days apart).


clj-time.predicates comes with a set of handy predicates to check for common conditions. For instance:

(require '[clj-time.core :as t])
(require '[clj-time.predicates :as pr])
(pr/monday? (t/date-time 1999 9 9))
=> false

(pr/january? (t/date-time 2011 1 1))
=> true

(pr/weekend? (t/date-time 2014 1 26))
=> true

(pr/weekday? (t/date-time 2014 1 26))
=> false

(pr/last-day-of-month? (t/date-time 2014 1 26))
=> false

(pr/first-day-of-month? (t/date-time 2014 1 26))
=> false


clj-time.jdbc registers protocol extensions so you don’t have to use clj-time.coerce yourself to coerce to and from SQL timestamps.

From the REPL:

(require 'clj-time.jdbc)

In your project:

(ns my.neat.project
  (:require [clj-time.jdbc]))

; They're registered and ready to use.

Now you can use org.joda.time.DateTime objects when "writing" to the database in place of java.sql.Timestamp objects, and expect org.joda.time.DateTime objects when "reading" where you would have previously expected java.sql.Timestamp objects.


Running the tests:

$ rm -f test/readme.clj && lein test-all && lein test-readme

(assumes Leiningen 2.x)


The complete API documentation is also available (codox generated).


Released under the MIT License: https://github.com/clj-time/clj-time/blob/master/MIT-LICENSE.txt