Time Difference: Chicago vs Tehran
Tehran is 8.5 hours ahead of Chicago.
Quick Reference
- Chicago
- CDT (GMT-5)
CST starts on Nov 1, 2026
- Tehran
- IRST (GMT+3:30)
No Daylight Saving Time
Frequently Asked Questions
- What is the time difference between Chicago and Tehran?
- Tehran is 8.5 hours ahead of Chicago.
- When is the best time to call from Chicago to Tehran?
- The best time to call is during overlapping business hours (9 AM – 5 PM) in both cities. Use the interactive converter on this page to visually compare hours side by side.
- Does the time difference change with daylight saving time?
- The time difference may change when either city enters or exits daylight saving time. Chicago uses CDT and Tehran uses IRST.