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

/tz
↵  
  • Chicago, US: 7:01 pm CST, Tue Dec 18th
  • Chicago is 1 hour behind you
  • Los Angeles, US: 5:01 pm PST, Tue Dec 18th
  • Los Angeles is 3 hours behind you
  • Paris, FR: 2:01 am CET, Wed Dec 19th
  • Paris is 6 hours ahead of you
  • Mumbai, IN: 6:31 am IST, Wed Dec 19th
  • Mumbai is 10.5 hours ahead of you
  • Chicago is 2 hours ahead of Los Angeles
  • Chicago is 7 hours behind Paris
  • Chicago is 11.5 hours behind Mumbai

Examples: