Does the time difference between Amsterdam and Chicago change during the year?

Yes. Because of daylight saving time the gap moves between +6h and +7h.

When is the best time to call Chicago from Amsterdam?

Between 16:00 and 17:00 in Amsterdam, which is 09:00 to 10:00 in Chicago.

Amsterdam is 7h ahead of Chicago. This gap is not fixed: daylight saving time moves it between +6h and +7h during the year.

Amsterdam

Netherlands

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Chicago

United States

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

City	Time zone	UTC offset
Amsterdam · Netherlands	Europe/Amsterdam	UTC+2
Chicago · United States	America/Chicago	UTC−5

What is the time difference between Amsterdam and Chicago?: Amsterdam is 7h ahead of Chicago. This gap is not fixed: daylight saving time moves it between +6h and +7h during the year.
Does the time difference between Amsterdam and Chicago change during the year?: Yes. Because of daylight saving time the gap moves between +6h and +7h.
When is the best time to call Chicago from Amsterdam?: Between 16:00 and 17:00 in Amsterdam, which is 09:00 to 10:00 in Chicago.