Upvote:0
A search in Timatic gives the following result:
Transit - Turkey (TR)
TWOV (Transit Without Visa): Passengers with a confirmed onward ticket for a flight to a third country within 24 hours. They must stay in the international transit area of the airport and have documents required for the next destination.
So you don't need a transit visa. (I am assuming that you will indeed be staying in the international transit area in Istanbul, i. e. both flights are on the same booking.)