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

Yes. Because of daylight saving time the gap moves between −6h and −5h.

When is the best time to call Bangkok from Amsterdam?

Between 09:00 and 12:00 in Amsterdam, which is 14:00 to 17:00 in Bangkok.

Amsterdam is 5h behind Bangkok. This gap is not fixed: daylight saving time moves it between −6h and −5h during the year.

Amsterdam

Netherlands

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Bangkok

Thailand

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A 9-to-5 day in each city overlaps for 3h. That is 09:00–12:00 in Amsterdam, which is 14:00–17:00 in Bangkok.

City	Time zone	UTC offset
Amsterdam · Netherlands	Europe/Amsterdam	UTC+2
Bangkok · Thailand	Asia/Bangkok	UTC+7

What is the time difference between Amsterdam and Bangkok?: Amsterdam is 5h behind Bangkok. This gap is not fixed: daylight saving time moves it between −6h and −5h during the year.
Does the time difference between Amsterdam and Bangkok change during the year?: Yes. Because of daylight saving time the gap moves between −6h and −5h.
When is the best time to call Bangkok from Amsterdam?: Between 09:00 and 12:00 in Amsterdam, which is 14:00 to 17:00 in Bangkok.