Does the time difference between Beijing and Dublin change during the year?

Yes. Because of daylight saving time the gap moves between +7h and +8h.

When is the best time to call Dublin from Beijing?

Between 16:00 and 17:00 in Beijing, which is 09:00 to 10:00 in Dublin.

Beijing is 7h ahead of Dublin. This gap is not fixed: daylight saving time moves it between +7h and +8h during the year.

Beijing

China

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Dublin

Ireland

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A 9-to-5 day in each city overlaps for 1h. That is 16:00–17:00 in Beijing, which is 09:00–10:00 in Dublin.

City	Time zone	UTC offset
Beijing · China	Asia/Shanghai	UTC+8
Dublin · Ireland	Europe/Dublin	UTC+1

What is the time difference between Beijing and Dublin?: Beijing is 7h ahead of Dublin. This gap is not fixed: daylight saving time moves it between +7h and +8h during the year.
Does the time difference between Beijing and Dublin change during the year?: Yes. Because of daylight saving time the gap moves between +7h and +8h.
When is the best time to call Dublin from Beijing?: Between 16:00 and 17:00 in Beijing, which is 09:00 to 10:00 in Dublin.