Does the time difference between Istanbul and Lagos change during the year?

No. The gap stays at 2h all year.

When is the best time to call Lagos from Istanbul?

Between 11:00 and 17:00 in Istanbul, which is 09:00 to 15:00 in Lagos.

Istanbul is 2h ahead of Lagos. This gap is the same all year — neither city shifts its clocks relative to the other.

Istanbul

Türkiye

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Lagos

Nigeria

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A 9-to-5 day in each city overlaps for 6h. That is 11:00–17:00 in Istanbul, which is 09:00–15:00 in Lagos.

City	Time zone	UTC offset
Istanbul · Türkiye	Europe/Istanbul	UTC+3
Lagos · Nigeria	Africa/Lagos	UTC+1

What is the time difference between Istanbul and Lagos?: Istanbul is 2h ahead of Lagos. This gap is the same all year — neither city shifts its clocks relative to the other.
Does the time difference between Istanbul and Lagos change during the year?: No. The gap stays at 2h all year.
When is the best time to call Lagos from Istanbul?: Between 11:00 and 17:00 in Istanbul, which is 09:00 to 15:00 in Lagos.