This gem provides utilities to help with migrations between timezone changes. Please check the official webpage for documentation: https://a0.github.io/a0-tzmigration/


Add this line to your application's Gemfile:

gem 'a0-tzmigration-ruby'

And then execute:

$ bundle

Or install it yourself as:

$ gem install a0-tzmigration-ruby


require 'a0-tzmigration-ruby'

# calculate changes from America/Santiago 2015a to America/Punta_Arenas 2017a
version_a = A0::TZMigration::TZVersion.new('America/Santiago', '2015a')
version_b = A0::TZMigration::TZVersion.new('America/Punta_Arenas', '2017a')

# =>
[{:ini_str=>"-∞", :fin_str=>"1890-01-01 04:43:40 UTC", :off_str=>"-00:00:54", :ini=>-Infinity, :fin=>-2524504580, :off=>-54},
 {:ini_str=>"1910-01-01 04:42:46 UTC", :fin_str=>"1910-01-10 04:42:46 UTC", :off_str=>"+00:17:14", :ini=>-1893439034, :fin=>-1892661434, :off=>1034},
 {:ini_str=>"1918-09-01 04:42:46 UTC", :fin_str=>"1918-09-10 04:42:46 UTC", :off_str=>"-00:42:46", :ini=>-1619983034, :fin=>-1619205434, :off=>-2566},
 {:ini_str=>"1946-09-01 03:00:00 UTC", :fin_str=>"1947-04-01 04:00:00 UTC", :off_str=>"+01:00:00", :ini=>-736376400, :fin=>-718056000, :off=>3600},
 {:ini_str=>"1947-05-22 04:00:00 UTC", :fin_str=>"1947-05-22 05:00:00 UTC", :off_str=>"+01:00:00", :ini=>-713649600, :fin=>-713646000, :off=>3600},
 {:ini_str=>"1988-10-02 04:00:00 UTC", :fin_str=>"1988-10-09 04:00:00 UTC", :off_str=>"-01:00:00", :ini=>591768000, :fin=>592372800, :off=>-3600},
 {:ini_str=>"1990-03-11 03:00:00 UTC", :fin_str=>"1990-03-18 03:00:00 UTC", :off_str=>"-01:00:00", :ini=>637124400, :fin=>637729200, :off=>-3600},
 {:ini_str=>"2016-05-15 03:00:00 UTC", :fin_str=>"2016-08-14 04:00:00 UTC", :off_str=>"-01:00:00", :ini=>1463281200, :fin=>1471147200, :off=>-3600}]

# get current known versions in the repository
# =>
  { "2013c" =>
    { "released_at" => "2013-04-19 16:17:40 -0700",
      "timezones" => [

# get current known timezones in the repository
# =>
  { "Africa/Abidjan" =>
    { "versions" => [


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.


Bug reports and pull requests are welcome on GitHub at https://github.com/a0/a0-tzmigration-ruby. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the A0::TZMigration project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.