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

/tz
↵  
  • Chicago, US: 8:57 pm CDT, Tue May 18th
  • Chicago is 1 hour behind you
  • Los Angeles, US: 6:57 pm PDT, Tue May 18th
  • Los Angeles is 3 hours behind you
  • Paris, FR: 3:57 am CEST, Wed May 19th
  • Paris is 6 hours ahead of you
  • Mumbai, IN: 7:27 am IST, Wed May 19th
  • 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: