Please be aware that Chicago has multiple airports and that these results are only for O'Hare International airport.
The best month to arrive at Chicago is November and the most expensive month to fly is March. (Average prices, based on 225 datapoints.)
The best day to arrive at Chicago is Saturday and it would be best to avoid Tuesday, as prices are on average 137.34% higher than on Saturday. (Average prices, based on 210 datapoints.)
The cheapest airline flying to Chicago is Air Canada. They are 88% cheaper than British Airways. (Average prices, based on 249 datapoints.)
At Chicago the most flights depart around 11:00. (Hourly flights, based on 309 datapoints.)
From Chicago it is on average the cheapest to fly to Toronto and to Frankfurt. (Average prices, based on 131 datapoints.)