Observatory log
Chicago and Sumy, compared
- 01Difference now
Sumy is 8 hours ahead of Chicago.
Chicago: CDT (UTC−5) · Sumy: EEST (UTC+3)
Next changeFrom 25 October 2026: Sumy is 7 hours ahead of Chicago.
- 02Through 2026–2027
- 1 January 2026 – 8 March 2026+8 h
- 8 March 2026 – 29 March 2026+7 h
- 29 March 2026 – 25 October 2026+8 h
- 25 October 2026 – 1 November 2026+7 h
- 1 November 2026 – 14 March 2027+8 h
- 14 March 2027 – 28 March 2027+7 h
- 28 March 2027 – 31 October 2027+8 h
- 31 October 2027 – 7 November 2027+7 h
- 7 November 2027 – 31 December 2027+8 h
Difference of Sumy 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
06:00–14:00 in Chicago = 14:00–22:00 in Sumy
No shared office hours: this is early or late for one side (Mon–Fri).
- 05Weekend
Chicago: Saturday and Sunday
Sumy: Saturday and Sunday
24 hours
A day in Chicago, in Sumy
| Chicago | Sumy | Working hours, evening, night or weekend in each place |
|---|---|---|
| 00:00 | 08:00 | |
| 01:00 | 09:00 | |
| 02:00 | 10:00 | |
| 03:00 | 11:00 | |
| 04:00 | 12:00 | |
| 05:00 | 13:00 | |
| 06:00 | 14:00 | |
| 07:00 | 15:00 | |
| 08:00 | 16:00 | |
| 09:00 | 17:00 | |
| 10:00 | 18:00 | |
| 11:00 | 19:00 | |
| 12:00 | 20:00 | |
| 13:00 | 21:00 | |
| 14:00 | 22:00 | |
| 15:00 | 23:00 | |
| 16:00 | 00:00Tomorrow | |
| 17:00 | 01:00Tomorrow | |
| 18:00 | 02:00Tomorrow | |
| 19:00 | 03:00Tomorrow | |
| 20:00 | 04:00Tomorrow | |
| 21:00 | 05:00Tomorrow | |
| 22:00 | 06:00Tomorrow | |
| 23:00 | 07:00Tomorrow |
Working hoursEarly or eveningNightWeekend
Plan a meeting: Chicago and Sumy
More time differences with Chicago
Questions
Asked about Chicago and Sumy
What is the time difference between Chicago and Sumy?
Sumy is 8 hours ahead of Chicago. This holds until 25 October 2026; then Sumy is 7 hours ahead of Chicago.
What is the best time for a call between Chicago and Sumy?
No shared office hours. The least awkward windows, early or late for one side: Mon–Fri: 06:00–14:00 in Chicago = 14:00–22:00 in Sumy · 8 h.
When does the time difference between Chicago and Sumy change?
In the next 12 months it changes on: 25 October 2026 (+7 h); 1 November 2026 (+8 h); 14 March 2027 (+7 h); 28 March 2027 (+8 h).