Chronic is a natural language date/time parser written in pure Ruby. See below for the wide variety of formats Chronic will parse.

$ gem install chronic

require 'chronic'

Time.now   #=> Sun Aug 27 23:18:25 PDT 2006

Chronic.parse('tomorrow')
  #=> Mon Aug 28 12:00:00 PDT 2006

Chronic.parse('monday', :context => :past)
  #=> Mon Aug 21 12:00:00 PDT 2006

Chronic.parse('this tuesday 5:00')
  #=> Tue Aug 29 17:00:00 PDT 2006

Chronic.parse('this tuesday 5:00', :ambiguous_time_range => :none)
  #=> Tue Aug 29 05:00:00 PDT 2006

Chronic.parse('may 27th', :now => Time.local(2000, 1, 1))
  #=> Sat May 27 12:00:00 PDT 2000

Chronic.parse('may 27th', :guess => false)
  #=> Sun May 27 00:00:00 PDT 2007..Mon May 28 00:00:00 PDT 2007

Chronic.parse('6/4/2012', :endian_precedence => :little)
  #=> Fri Apr 06 00:00:00 PDT 2012

See Chronic.parse for detailed usage instructions.

Chronic can parse a huge variety of date and time formats. Following is a small sample of strings that will be properly parsed. Parsing is case insensitive and will handle common abbreviations and misspellings.

Simple

• thursday
• november
• summer
• friday 13:00
• mon 2:35
• 4pm
• 10 to 8
• 10 past 2
• half past 2
• 6 in the morning
• friday 1pm
• sat 7 in the evening
• yesterday
• today
• tomorrow
• last week
• next week
• this tuesday
• next month
• last winter
• this morning
• last night
• this second
• yesterday at 4:00
• last friday at 20:00
• last week tuesday
• tomorrow at 6:45pm
• afternoon yesterday
• thursday last week

Complex

• 3 years ago
• a year ago
• 5 months before now
• 7 hours ago
• 7 days from now
• 1 week hence
• in 3 hours
• 1 year ago tomorrow
• 3 months ago saturday at 5:00 pm
• 7 hours before tomorrow at noon
• 3rd wednesday in november
• 3rd month next year
• 3rd thursday this september
• 4th day last week
• fourteenth of june 2010 at eleven o'clock in the evening
• may seventh '97 at three in the morning

Specific Dates

• January 5
• 22nd of june
• 5th may 2017
• February twenty first
• dec 25
• may 27th
• October 2006
• oct 06
• jan 3 2010
• february 14, 2004
• february 14th, 2004
• 3 jan 2000
• 17 april 85
• 5/27/1979
• 27/5/1979
• 05/06
• 1979-05-27
• Friday
• 5
• 4:00
• 17:00
• 0800

Specific Times (many of the above with an added time)

• January 5 at 7pm
• 22nd of june at 8am
• 1979-05-27 05:00:00
• etc

Chronic allows you to set which Time class to use when constructing times. By default, the built in Ruby time class creates times in your system's local time zone. You can set this to something like ActiveSupport's TimeZone class to get full time zone support.

>> Time.zone = "UTC"
>> Chronic.time_class = Time.zone
>> Chronic.parse("June 15 2006 at 5:45 AM")
=> Thu, 15 Jun 2006 05:45:00 UTC +00:00

Chronic uses Ruby's built in Time class for all time storage and computation. Because of this, only times that the Time class can handle will be properly parsed. Parsing for times outside of this range will simply return nil. Support for a wider range of times is planned for a future release.

If you'd like to hack on Chronic, start by forking the repo on GitHub:

https://github.com/mojombo/chronic

The best way to get your changes merged back into core is as follows:

1. Clone down your fork
2. Create a thoughtfully named topic branch to contain your change
3. Hack away
4. Add tests and make sure everything still passes by running rake
5. Ensure your tests pass in multiple timezones. ie TZ=utc rake TZ=BST rake
6. If you are adding new functionality, document it in the README
7. Do not change the version number, we will do that on our end
8. If necessary, rebase your commits into logical chunks, without errors
9. Push the branch up to GitHub
10. Send a pull request for your branch