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