Cheap flights from London to Illinois from £336

The month of September is, on average, the cheapest month to fly to Illinois from London, with most prices found around £412. If you aren’t able to travel to Illinois during the month of September, then flying in November is also cheap. Prices for this month can be found on momondo for an average of £476.

The cheapest day to depart on your flight to Illinois is on a Wednesday when prices can be found for as low as £637. This is often the case because there is less demand to fly during this day of the week. Flights from London to Illinois on a Sunday will generally be more expensive and average around £667. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

Our data shows that the cheapest London to Illinois flights are usually those with departure times at midday. Our users have found flights to Illinois at midday for as low as £635. In the afternoon is when there is more demand to fly to Illinois, so prices are often more expensive at around £661 per ticket.

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 £568 when searching weeks before you fly. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from London for as low as £443 on momondo.

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

British Airways, Lufthansa and Icelandair 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 61% of people opting to fly with this airline when travelling to Illinois. Keep in mind that there are 14 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 49 per day as of May 2026. The most frequent departure time is 14:00, with 54% of daily flights leaving in the afternoon.

The number of flights available between London and Illinois is 343 per week as of May 2026. The most frequent departure day is Sun, with 17% of weekly flights leaving on this day.