Observatory log
Chicago and Semnan, compared
- 01Difference now
Semnan is 8 hours 30 minutes ahead of Chicago.
Chicago: CDT (UTC−5) · Semnan: UTC+3:30 (UTC+3:30)
Next changeFrom 1 November 2026: Semnan is 9 hours 30 minutes ahead of Chicago.
- 02Through 2026–2027
- 1 January 2026 – 8 March 2026+9 h 30 min
- 8 March 2026 – 1 November 2026+8 h 30 min
- 1 November 2026 – 14 March 2027+9 h 30 min
- 14 March 2027 – 7 November 2027+8 h 30 min
- 7 November 2027 – 31 December 2027+9 h 30 min
Difference of Semnan from Chicago. It changes on the days either place changes its clocks (dates local to that place).
- 03Shared working hours
Their working days never overlap.
Counted as 09:00–17:00 local time on each place’s own working days, for the next seven days.
- 04Best time to meet
09:00–13:30 in Chicago = 17:30–22:00 in Semnan
No shared office hours: this is early or late for one side (Mon–Thu).
Also possible: Mon–Thu: 06:00–08:30 in Chicago = 14:30–17:00 in Semnan · 2 h 30 min.
- 05Weekend
Chicago: Saturday and Sunday
Semnan: Friday
24 hours
A day in Chicago, in Semnan
| Chicago | Semnan | Working hours, evening, night or weekend in each place |
|---|---|---|
| 00:00 | 08:30 | |
| 01:00 | 09:30 | |
| 02:00 | 10:30 | |
| 03:00 | 11:30 | |
| 04:00 | 12:30 | |
| 05:00 | 13:30 | |
| 06:00 | 14:30 | |
| 07:00 | 15:30 | |
| 08:00 | 16:30 | |
| 09:00 | 17:30 | |
| 10:00 | 18:30 | |
| 11:00 | 19:30 | |
| 12:00 | 20:30 | |
| 13:00 | 21:30 | |
| 14:00 | 22:30 | |
| 15:00 | 23:30 | |
| 16:00 | 00:30Tomorrow | |
| 17:00 | 01:30Tomorrow | |
| 18:00 | 02:30Tomorrow | |
| 19:00 | 03:30Tomorrow | |
| 20:00 | 04:30Tomorrow | |
| 21:00 | 05:30Tomorrow | |
| 22:00 | 06:30Tomorrow | |
| 23:00 | 07:30Tomorrow |
Working hoursEarly or eveningNightWeekend
Plan a meeting: Chicago and Semnan
More time differences with Chicago
Questions
Asked about Chicago and Semnan
What is the time difference between Chicago and Semnan?
Semnan is 8 hours 30 minutes ahead of Chicago. This holds until 1 November 2026; then Semnan is 9 hours 30 minutes ahead of Chicago.
What is the best time for a call between Chicago and Semnan?
No shared office hours. The least awkward windows, early or late for one side: Mon–Thu: 09:00–13:30 in Chicago = 17:30–22:00 in Semnan · 4 h 30 min; Mon–Thu: 06:00–08:30 in Chicago = 14:30–17:00 in Semnan · 2 h 30 min.
When does the time difference between Chicago and Semnan change?
In the next 12 months it changes on: 1 November 2026 (+9 h 30 min); 14 March 2027 (+8 h 30 min).