Converting time stamps in excel to dates

Use this formula and set formatting to the desired time format:

=(((COLUMN_ID_HERE/60)/60)/24)+DATE(1970,1,1)

Source: http://www.bajb.net/2010/05/excel-timestamp-to-date/ Tested in libreoffice

A timestamp is the elapsed time since Epoch time (01/01/1970), so basically we have to convert this time in days, and add the epoch time, to get a valid format for any Excel like spreadsheet software.

• From a timestamp in milliseconds (ex: 1488380243994)

  use this formula:

  =A1/1000/86400+25569
  

  with this formater:

  yyyy-mm-dd hh:mm:ss.000
  

• From a timestamp in seconds (ex: 1488380243)

  use this formula:

  =A1/86400+25569
  

  with this formater:

  yyyy-mm-dd hh:mm:ss
  

Where A1 is your column identifier. Given custom formaters allow to not loose precision in displayed data, but you can of course use any other date/time one that corresponds to your needs.