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

/tz
↵  
  • Chicago, US: 10:40 pm CST, Sat Dec 14th
  • Chicago is 1 hour behind you
  • Los Angeles, US: 8:40 pm PST, Sat Dec 14th
  • Los Angeles is 3 hours behind you
  • Paris, FR: 5:40 am CET, Sun Dec 15th
  • Paris is 6 hours ahead of you
  • Mumbai, IN: 10:10 am IST, Sun Dec 15th
  • 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: