Cheap flights from London to Illinois from $369

The cheapest month to fly to Illinois from London is in September. Flight prices, which tend to average around $577, are often lower during this time because this is during the off-season. If you aren’t able to travel to Illinois during the month of September, then flying in February is also cheap. Prices for this month can be found on momondo for an average of $580.

The cheapest day to depart from London to Illinois is on a Wednesday when prices can be found for as low as $799. Flights from London to Illinois on a Monday will generally be more expensive and average around $900. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

Our most recent data shows that the best time of day to fly to Illinois is in the morning. Flights from London to Illinois during this time can be as low as $830. Flights in the afternoon are often more expensive with an average ticket price of $940.

Fly from London Heathrow to Chicago O'Hare Intl for the best London - Illinois flight prices

You are more likely to see cheaper flights to Illinois from London when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $743 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from London for as low as $621 on momondo.

There are 4 cabin classes available to choose from on London to Illinois flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Air Canada, SWISS, and United Airlines are the most popular carriers operating from London to Illinois

British Airways, American Airlines and Aer Lingus are the top three most popular airlines that fly to Illinois from London according to our data. British Airways is the first choice among our users, with 53% of people opting to fly with this airline when traveling to Illinois. Keep in mind that there are 9 different airlines that fly to Illinois on a routine basis, so you have a few additional options to choose from.

The number of flights available between London and Illinois is 36 per day as of March 2026. The most frequent departure time is 12:00PM, with 64% of daily flights leaving in the afternoon.

The number of flights available between London and Illinois is 256 per week as of March 2026. The most frequent departure day is Wed, with 18% of weekly flights leaving on this day.