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Editorial Team
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Asked: 2026-06-14T04:35:08+00:00

I’m using ActiveSupport’s Timezone class to find the offset of a Timezone like so.

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I’m using ActiveSupport’s Timezone class to find the offset of a Timezone like so. 

novdate = Date.new(2012,11,04)
offset_in_seconds = ActiveSupport::TimeZone['Eastern Time (US & Canada)'].at(novdate.to_time.midnight+3.hours).utc_offset

The problem is that offset_in_seconds is different on my local machine and on a heroku server. I’m not sure why this is happening. I’ve set config.time_zone = ‘Eastern Time (US & Canada)’ in my rails application.rb file. How can I accurately and consistently get a timezone offset for a given date? I’ve been adding 3 hours to the time above because the time should have been changed from DST to non-DST at 3:00am on a given date.

— display from my local rails console —

novdate = Date.new(2012,11,04)
ActiveSupport::TimeZone['Eastern Time (US & Canada)'].at(novdate.to_time.midnight+1.hours)
 => Sun, 04 Nov 2012 01:00:00 EDT -04:00 
ActiveSupport::TimeZone['Eastern Time (US & Canada)'].at(novdate.to_time.midnight+2.hours)
 => Sun, 04 Nov 2012 01:00:00 EST -05:00 
ActiveSupport::TimeZone['Eastern Time (US & Canada)'].at(novdate.to_time.midnight+3.hours)
 => Sun, 04 Nov 2012 02:00:00 EST -05:00

— output from a heroku rails console —

ActiveSupport::TimeZone['Eastern Time (US & Canada)'].at(novdate.to_time.midnight+4.hours)
=> Sun, 04 Nov 2012 00:00:00 EDT -04:00
ActiveSupport::TimeZone['Eastern Time (US & Canada)'].at(novdate.to_time.midnight+5.hours)
=> Sun, 04 Nov 2012 01:00:00 EDT -04:00
ActiveSupport::TimeZone['Eastern Time (US & Canada)'].at(novdate.to_time.midnight+6.hours)
=> Sun, 04 Nov 2012 01:00:00 EST -05:00
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1 Answer

  1. Editorial Team

    The problem here is the to_time method of date will not respect your timezone with that syntax.

    If you look at the documentation for to_time you can see it converts it to local time to the server.

    Chances are the heroku server has a different time zone configured to your local machine (note this is not the config.time_zone setting)

    This should work: 

    [24] pry(main)> Time.use_zone('Eastern Time (US & Canada)') {
[24] pry(main)*   novdate.to_time_in_current_zone()  
[24] pry(main)* }  
=> Sun, 04 Nov 2012 00:00:00 EDT -04:00
[25] pry(main)>
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