Shanghai is 1 hour behind Seoul for most of the year: when it is 10:00 am in Seoul it is 9:00 am in Shanghai. In offset terms Seoul is on UTC+09:00 and Shanghai is on UTC+08:00 in January, and UTC+09:00 and UTC+08:00 in July. The converter above works from your browser’s own time zone data, so the figure it shows is the one in force today rather than the one that was in force when this page was written.
Neither city changes its clocks. Seoul stays on UTC+09:00 and Shanghai stays on UTC+08:00 all year. The difference is therefore fixed for all of 2026, which makes this one of the few city pairs where a single number is the whole answer: Shanghai is always 1 hour behind Seoul. Recurring meetings between the two never drift, and the table below confirms it period by period.
For arranging anything, the number that matters is the overlap. Seoul works 09:00 to 18:00 and Shanghai works 09:00 to 18:00, which leaves 10:00 to 18:00 in Seoul — 09:00 to 17:00 in Shanghai — as the window when both are open. That is 8 hours of shared working time. Both cities work Monday to Friday, so only the clock has to be reconciled.
Two local details worth knowing. Korea keeps UTC+09:00 year-round, the same clock as Japan, so the two are interchangeable for scheduling. China uses one zone, UTC+08:00, from Kashgar to Shanghai, and a long midday break is still normal outside the largest firms.
The safest way to write a time for these two cities is to give both, as in "10:00 Seoul / 09:00 Shanghai", or to give the UTC offset. Abbreviations are the trap: Seoul is on KST for part of the year and KST for the rest, and the same three letters are reused in other parts of the world for entirely different offsets.
The formula
local Seoul- The time you enter, on the Seoul clock
offset- Each city’s UTC offset at that moment, read live from the IANA time zone database in your browser
−1- The difference in hours that holds for most of 2026: Shanghai is 1 hour behind Seoul
day shift- Whether the converted time falls on the previous, same or next calendar day in Shanghai
How it works, step by step
- Enter a time in Seoul using the 24-hour hour box and the minute box — 15:30 is hour 15, minute 30.
- Your browser reports the UTC offset in force in Seoul and in Shanghai for that moment, so a date near a daylight saving transition is handled correctly rather than with a fixed 1 hour rule.
- The second offset minus the first gives the difference, which is added to the time you entered. A result past midnight is marked as the next or previous day, because that is where most conversion mistakes live.
- The panel also shows the current time in both cities, the date in Shanghai, and whether the two offices are open at the same moment.
Worked examples
09:00 in Seoul
09:00 in Seoul is 08:00 in Shanghai — before the working day starts in Shanghai. In 12-hour terms, 9:00 am against 8:00 am. Only one of the two offices is open at that moment, so it is worth offering rather than assuming.
12:00 in Seoul
12:00 in Seoul is 11:00 in Shanghai — inside Shanghai office hours. In 12-hour terms, 12:00 pm against 11:00 am. Both offices are open at that moment, so it is a slot either side can accept.
17:00 in Seoul
17:00 in Seoul is 16:00 in Shanghai — inside Shanghai office hours. In 12-hour terms, 5:00 pm against 4:00 pm. Both offices are open at that moment, so it is a slot either side can accept.
23:00 in Seoul, and the date problem
23:00 in Seoul is 22:00 in Shanghai on the same day. This is where conversions go wrong in writing: the time is right, the day is not, and a meeting invitation sent for "Tuesday" arrives for the wrong Tuesday. Give the date in both cities whenever the converted time is near midnight.
How to read your score
Frequently asked questions
How many hours behind Seoul is Shanghai?
Shanghai is 1 hour behind Seoul for most of 2026, so 09:00 in Seoul is 08:00 in Shanghai. That difference holds for the whole year, because the two clocks either never change or change on the same dates — the table on this page confirms it period by period.
What is 2 pm Seoul time in Shanghai?
1:00 pm, inside Shanghai office hours. In 24-hour form 14:00 in Seoul is 13:00 in Shanghai, and that is a normal working moment in both cities.
What is the best time to call between Seoul and Shanghai?
Anywhere between 10:00 and 18:00 Seoul time, which is 09:00 to 17:00 in Shanghai. Both offices are open across that whole window — 8 hours of it. If you want one answer rather than a range, 14:00 in Seoul is the middle of the overlap.
Is Shanghai ahead of or behind Seoul?
Shanghai is behind. Seoul is at UTC+09:00 and Shanghai is at UTC+08:00 in mid-January, and UTC+09:00 and UTC+08:00 in mid-July. The clock moves back going from Seoul to Shanghai, which is why Seoul reaches the end of its working day first.
Do Seoul and Shanghai change their clocks on the same date?
Neither city changes its clocks. In 2026, Seoul does not change its clocks at all, and Shanghai does not change its clocks at all. The difference between the two cities therefore holds all year.
What do the abbreviations for Seoul mean?
Seoul is on KST in winter and KST in summer, while Shanghai uses CST and CST. Abbreviations are the least reliable way to write a time: several are ambiguous between regions, and the summer and winter forms are an hour apart. A UTC offset, or the time given in both cities, cannot be misread.
Does this converter stay correct after the clocks change?
Yes. It does not use a stored number for the difference. Each time you change a value it asks your browser for the UTC offset that Asia/Seoul and Asia/Shanghai are on at that moment, using the IANA time zone database that ships with your operating system, and takes the difference. The tables on this page are computed from the same database for 2026.
Seoul to Shanghai: every hour, every period of 2026, and meeting slots
| Seoul (24h) | Seoul (12h) | Shanghai (24h) | Shanghai (12h) | Status |
|---|---|---|---|---|
| 00:00 | 12:00 am | 23:00 (previous day) | 11:00 pm (previous day) | outside office hours |
| 01:00 | 1:00 am | 00:00 | 12:00 am | outside office hours |
| 02:00 | 2:00 am | 01:00 | 1:00 am | outside office hours |
| 03:00 | 3:00 am | 02:00 | 2:00 am | outside office hours |
| 04:00 | 4:00 am | 03:00 | 3:00 am | outside office hours |
| 05:00 | 5:00 am | 04:00 | 4:00 am | outside office hours |
| 06:00 | 6:00 am | 05:00 | 5:00 am | outside office hours |
| 07:00 | 7:00 am | 06:00 | 6:00 am | outside office hours |
| 08:00 | 8:00 am | 07:00 | 7:00 am | outside office hours |
| 09:00 | 9:00 am | 08:00 | 8:00 am | office hours in Seoul |
| 10:00 | 10:00 am | 09:00 | 9:00 am | office hours in both |
| 11:00 | 11:00 am | 10:00 | 10:00 am | office hours in both |
| 12:00 | 12:00 pm | 11:00 | 11:00 am | office hours in both |
| 13:00 | 1:00 pm | 12:00 | 12:00 pm | office hours in both |
| 14:00 | 2:00 pm | 13:00 | 1:00 pm | office hours in both |
| 15:00 | 3:00 pm | 14:00 | 2:00 pm | office hours in both |
| 16:00 | 4:00 pm | 15:00 | 3:00 pm | office hours in both |
| 17:00 | 5:00 pm | 16:00 | 4:00 pm | office hours in both |
| 18:00 | 6:00 pm | 17:00 | 5:00 pm | office hours in Shanghai |
| 19:00 | 7:00 pm | 18:00 | 6:00 pm | outside office hours |
| 20:00 | 8:00 pm | 19:00 | 7:00 pm | outside office hours |
| 21:00 | 9:00 pm | 20:00 | 8:00 pm | outside office hours |
| 22:00 | 10:00 pm | 21:00 | 9:00 pm | outside office hours |
| 23:00 | 11:00 pm | 22:00 | 10:00 pm | outside office hours |
Computed at a difference of -1 hours, which is the one that holds for most of 2026. During the transition windows in the table below, shift the right-hand columns by an hour.
| Period | Length | Seoul offset | Shanghai offset | Difference | Abbreviations |
|---|---|---|---|---|---|
| 01 Jan to 31 Dec | 365 days | UTC+09:00 | UTC+08:00 | -1:00 | KST / CST |
Every row is read from the IANA time zone database. Short periods appear where one city has changed its clocks and the other has not yet done so.
| Seoul | 12-hour | Shanghai | Verdict |
|---|---|---|---|
| 06:00 | 6:00 am | 05:00 | Outside both |
| 06:30 | 6:30 am | 05:30 | Outside both |
| 07:00 | 7:00 am | 06:00 | Outside both |
| 07:30 | 7:30 am | 06:30 | Outside both |
| 08:00 | 8:00 am | 07:00 | Outside both |
| 08:30 | 8:30 am | 07:30 | Outside both |
| 09:00 | 9:00 am | 08:00 | Too early in Shanghai |
| 09:30 | 9:30 am | 08:30 | Too early in Shanghai |
| 10:00 | 10:00 am | 09:00 | Good — both offices open |
| 10:30 | 10:30 am | 09:30 | Good — both offices open |
| 11:00 | 11:00 am | 10:00 | Good — both offices open |
| 11:30 | 11:30 am | 10:30 | Good — both offices open |
| 12:00 | 12:00 pm | 11:00 | Good — both offices open |
| 12:30 | 12:30 pm | 11:30 | Good — both offices open |
| 13:00 | 1:00 pm | 12:00 | Good — both offices open |
| 13:30 | 1:30 pm | 12:30 | Good — both offices open |
| 14:00 | 2:00 pm | 13:00 | Good — both offices open |
| 14:30 | 2:30 pm | 13:30 | Good — both offices open |
| 15:00 | 3:00 pm | 14:00 | Good — both offices open |
| 15:30 | 3:30 pm | 14:30 | Good — both offices open |
| 16:00 | 4:00 pm | 15:00 | Good — both offices open |
| 16:30 | 4:30 pm | 15:30 | Good — both offices open |
| 17:00 | 5:00 pm | 16:00 | Good — both offices open |
| 17:30 | 5:30 pm | 16:30 | Good — both offices open |
| 18:00 | 6:00 pm | 17:00 | After hours in Seoul |
| 18:30 | 6:30 pm | 17:30 | After hours in Seoul |
| 19:00 | 7:00 pm | 18:00 | Outside both |
| 19:30 | 7:30 pm | 18:30 | Outside both |
| 20:00 | 8:00 pm | 19:00 | Outside both |
| 20:30 | 8:30 pm | 19:30 | Outside both |
| 21:00 | 9:00 pm | 20:00 | Outside both |
| 21:30 | 9:30 pm | 20:30 | Outside both |
Office hours taken as 09:00–18:00 in Seoul and 09:00–18:00 in Shanghai, which are the customary hours in each city rather than a generic nine to five.