Set it up in Slack or give it a try below:

/tz
↵  
  • Chicago, US: 5:56 pm CDT, Thu Jun 17th
  • Chicago is 1 hour behind you
  • Los Angeles, US: 3:56 pm PDT, Thu Jun 17th
  • Los Angeles is 3 hours behind you
  • Paris, FR: 12:56 am CEST, Fri Jun 18th
  • Paris is 6 hours ahead of you
  • Mumbai, IN: 4:26 am IST, Fri Jun 18th
  • Mumbai is 9.5 hours ahead of you
  • Chicago is 2 hours ahead of Los Angeles
  • Chicago is 7 hours behind Paris
  • Chicago is 10.5 hours behind Mumbai

Examples: