Cheap flights from Illinois to London from £234

In general, January is the cheapest month to fly from Illinois to London Heathrow Airport. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around £479. The month of February is another great option to travel to London Heathrow Airport, with average flight prices from Illinois averaging around £541.

On average, the least expensive day to fly to London Heathrow Airport from Illinois is on a Monday. momondo users have found tickets for Monday departures for as low as £672. However, this price may fluctuate depending on the airline, the season, and holidays. Be sure to avoid booking your departure on a Saturday as prices are generally higher than usual. According to our data, the average ticket price to London Heathrow Airport on Saturday is £1,037.

According to our data, the cheapest time of day to fly to London Heathrow Airport is in the evening. momondo users have found flights departing from Illinois to London Heathrow Airport in the evening for as low as £835. Keep in mind that these prices may fluctuate based on what airline you choose and the time of year you plan to travel. If you have a flexible travel schedule, then try to avoid flying in the afternoon when prices are £892 on average. Flights to London Heathrow Airport from Illinois in the afternoon are generally more expensive because this time of day is more convenient for travellers’ schedules.

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

You are more likely to see cheaper flights to London Heathrow Airport from Illinois when booking weeks ahead of your departure date. In general, you can expect to find flights to London Heathrow Airport for around £688 when searching weeks before you fly. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London Heathrow Airport from Illinois for as low as £642 on momondo.

There are 3 cabin classes available to choose from on Illinois to London Heathrow Airport flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Icelandair, SWISS, and Lufthansa are the most popular carriers operating from Illinois to London Heathrow

British Airways, Aer Lingus and United Airlines are the top three most popular airlines that fly to London Heathrow Airport from Illinois according to our data. British Airways is the first choice among our users, with 35% of people opting to fly with this airline when travelling to London Heathrow Airport. Keep in mind that there are 7 different airlines that fly to London Heathrow Airport on a routine basis, so you have a few additional options to choose from.

As of October 2026, 44 flights take off from Illinois and land in London Heathrow Airport each day. The most common flight departure time for this route is 17:00, with 60% of daily flights taking off in the evening.

As of October 2026, 314 flights take off from Illinois and land in London Heathrow Airport each week. The most common flight departure day for this route is Wed, with 18% of weekly flights taking off on this day.