Please be aware that Brussels and Istanbul has multiple airports and that these results are for all airports serving the city.
The best month to fly between Brussels and Istanbul is January and the most expensive month to fly is December. (Average prices, based on 303 datapoints.)
The best day to arrive at Brussels is Wednesday and it would be best to avoid Saturday, as prices are on average 90.86% higher than on Wednesday. (Average prices, based on 387 datapoints.)
The best time to fly is at around 13. (Average prices, based on 584 datapoints.)