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

No. The gap stays at 1h 30m all year.

When is the best time to call Bangkok from Bangalore?

Between 09:00 and 15:30 in Bangalore, which is 10:30 to 17:00 in Bangkok.

Bangalore is 1h 30m behind Bangkok. This gap is the same all year — neither city shifts its clocks relative to the other.

Bangalore

India

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Bangkok

Thailand

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A 9-to-5 day in each city overlaps for 6h 30m. That is 09:00–15:30 in Bangalore, which is 10:30–17:00 in Bangkok.

City	Time zone	UTC offset
Bangalore · India	Asia/Kolkata	UTC+5:30
Bangkok · Thailand	Asia/Bangkok	UTC+7

What is the time difference between Bangalore and Bangkok?: Bangalore is 1h 30m behind Bangkok. This gap is the same all year — neither city shifts its clocks relative to the other.
Does the time difference between Bangalore and Bangkok change during the year?: No. The gap stays at 1h 30m all year.
When is the best time to call Bangkok from Bangalore?: Between 09:00 and 15:30 in Bangalore, which is 10:30 to 17:00 in Bangkok.