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 Izmir is January and the most expensive month to fly is May. (Average prices, based on 378 datapoints.)
The best day to arrive at Istanbul is Thursday and it would be best to avoid Saturday, as prices are on average 184.15% higher than on Thursday. (Average prices, based on 452 datapoints.)
The cheapest airline flying from Istanbul to Izmir is ValuAir. They are 24% cheaper than Turkish Airlines. (Average prices, based on 397 datapoints.)