Please be aware that Istanbul has multiple airports and that these results are for all airports serving the city.
The best month to fly between Istanbul and Amsterdam is February and the most expensive month to fly is August. (Average prices, based on 746 datapoints.)
The best day to arrive at Istanbul is Wednesday and it would be best to avoid Saturday, as prices are on average 81.7% higher than on Wednesday. (Average prices, based on 746 datapoints.)
The cheapest airline flying from Istanbul to Amsterdam is ValuAir. They are 26% cheaper than KLM. (Average prices, based on 753 datapoints.)