How long is the flight from London Heathrow Airport to Illinois?

Departing from London Heathrow Airport to Illinois will take you 9h 15m. The distance from London Heathrow Airport to Illinois is about 3939 mi. Both multi-stop and direct flights can be found to your destination and back.

What are the cheapest airlines to fly from London Heathrow Airport to Illinois one-way?

One-way options have recently been found by users for as low as £316 on JetBlue. Other airlines that offer cheap prices include Aer Lingus from £320 and Austrian Airlines from £328 one-way.

In terms of precipitation, rainfall in Illinois ranges from 43.0 - 125.0 inches per month. August is typically the wettest month, when rainfall can reach 125.0 mm. January is typically the driest time to visit Illinois when rainfall is around 43.0 mm.

If weather is an important factor for your trip to Illinois, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 23.0 C. Travellers hoping to avoid the cold should look outside of January, when temperatures are typically at their lowest (around -5.0 C).

What are the most popular routes from London Heathrow Airport to Illinois?

The most popular flight routes from London Heathrow Airport to Illinois are London Heathrow - Chicago O'Hare Intl, London Heathrow - Chicago Midway and London Heathrow - Lambert-St Louis.

What are the cheapest flights from London Heathrow Airport to Illinois?

Looking at all options, your cheapest flight can be booked for £406. While the most popular route (London Heathrow - Chicago O'Hare Intl) can be booked for £377 on average, our data indicates £1,584 when flying from London Heathrow Airport to Illinois.

What are the most reliable airlines from London Heathrow Airport to Illinois?

Before booking your flight to Illinois from London Heathrow Airport, check out the most reliable airlines to get you to your destination on time: Air Canada (88%), Austrian Airlines (88%), United Airlines( 88%).

What are the most popular airlines that fly from London Heathrow Airport to Illinois?

When booking a flight from London Heathrow Airport to Illinois, you may want to consider flying on British Airways, Lufthansa or Icelandair as they are the most popular for this route.

Can I find deals for flights from Heathrow to Illinois that include hotel bookings?

Yes. In addition to deals on Heathrow to Illinois flights, Cheapflights offers holiday packages that include both flights and hotel.

How can I find direct flights from Heathrow to Illinois?

After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Heathrow to Illinois.

Can I find deals for business class flights from Heathrow to Illinois?

Yes. Cheapflights offers flight deals from Heathrow to Illinois by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

£358+ Cheap Flights from London Heathrow Airport to Illinois

Cheap flight deals from Heathrow to Illinois

Enter your travel dates to find the best prices.

Cheapest

Best

Direct

Last-minute

One-way

Cheapest flights from Heathrow to Illinois
Explore the most affordable flight options available from Heathrow to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 3 October 2026.

Fri 25/1212:15 -

1 stop11h 05m

Sat 16/119:25 -

1 stop9h 25m

Deal found 29/9£534

Sun 15/1121:05 -

2 stops25h 40m

Sun 29/1119:10 -

1 stop17h 20m

Deal found 30/9£535

Fri 11/1207:05 -

2 stops15h 40m

Sat 9/119:10 -

2 stops15h 15m

Deal found 29/9£535

Thu 24/1212:15 -

1 stop11h 05m

Thu 14/118:30 -

1 stop10h 20m

Deal found 29/9£536

Thu 29/1012:15 -

1 stop11h 05m

Mon 2/1118:30 -

1 stop10h 20m

Deal found 29/9£537

Thu 3/1212:15 -

1 stop11h 05m

Fri 16/419:25 -

1 stop18h 55m

Deal found 28/9£538

Tue 20/1021:25 -

1 stop26h 50m

Wed 2/1218:30 -

1 stop19h 00m

Deal found 29/9£539

Fri 4/1220:35 -

1 stop26h 45m

Fri 16/419:25 -

1 stop18h 55m

Deal found 28/9£539

Thu 24/1212:15 -

1 stop11h 05m

Mon 28/1218:30 -

1 stop10h 20m

Deal found 28/9£540

Sat 31/1008:50 -

1 stop11h 20m

Wed 4/1115:55 -

1 stop10h 10m

Deal found 29/9£541

Thu 24/1212:15 -

1 stop11h 05m

Sun 10/118:30 -

1 stop10h 20m

Deal found 29/9£542

Wed 28/1007:05 -

2 stops15h 40m

Fri 13/1119:10 -

2 stops31h 45m

Deal found 1/10£542

Best flights from Heathrow to Illinois
Discover carefully curated flight deals from Heathrow to Illinois that have cost, travel time, and stopovers in mind to ensure you get the best travel experience. Data last updated 3 October 2026.

Wed 28/1006:40 -

1 stop16h 05m

Mon 9/1119:10 -

2 stops20h 25m

Deal found 1/10£548

Thu 8/1014:10 -

Nonstop9h 15m

Wed 21/1018:05 -

Nonstop8h 25m

Deal found 29/9£579

Wed 7/1006:30 -

2 stops16h 17m

Wed 14/1013:27 -

1 stop11h 43m

Deal found 29/9£587

Sun 15/1109:05 -

1 stop34h 55m

Sun 22/1115:45 -

Nonstop8h 10m

Deal found 1/10£635

Wed 25/1106:20 -

2 stops17h 44m

Tue 1/1210:24 -

2 stops14h 26m

Deal found 30/9£642

Wed 14/1014:45 -

1 stop15h 24m

Wed 21/1014:59 -

1 stop15h 16m

Deal found 30/9£843

Wed 14/1007:50 -

2 stops22h 19m

Wed 21/1014:59 -

1 stop10h 56m

Deal found 30/9£856

Fri 16/1014:10 -

1 stop14h 48m

Sat 24/1015:41 -

1 stop15h 19m

Deal found 1/10£906

Fri 16/1014:45 -

1 stop15h 14m

Tue 20/1014:30 -

1 stop11h 35m

Deal found 30/9£1,004

Wed 25/1110:20 -

1 stop12h 25m

Tue 1/1219:10 -

2 stops20h 25m

Deal found 30/9£550

Wed 21/1007:05 -

2 stops15h 05m

Mon 30/1119:10 -

2 stops20h 25m

Deal found 30/9£556

Mon 23/1111:10 -

1 stop13h 15m

Mon 7/1215:45 -

Nonstop8h 10m

Deal found 3/10£624

Mon 2/1106:30 -

2 stops17h 30m

Mon 16/1117:13 -

1 stop12h 27m

Deal found 2/10£656

Mon 2/1106:20 -

2 stops17h 40m

Mon 16/1113:31 -

2 stops13h 29m

Deal found 3/10£662

Wed 28/1006:40 -

1 stop16h 05m

Sat 7/1119:10 -

2 stops20h 10m

Deal found 1/10£566

Mon 26/1007:50 -

Nonstop9h 05m

Mon 2/1119:45 -

1 stop19h 35m

Deal found 28/9£629

Mon 26/1008:55 -

1 stop18h 38m

Mon 2/1111:38 -

2 stops13h 42m

Deal found 28/9£700

Wed 16/1211:20 -

1 stop12h 41m

Wed 6/110:35 -

1 stop13h 50m

Deal found 29/9£701

Tue 1/1209:00 -

1 stop13h 15m

Wed 14/418:10 -

Nonstop8h 20m

Deal found 28/9£650

Wed 21/1007:05 -

2 stops15h 05m

Wed 11/1119:10 -

1 stop17h 20m

Deal found 1/10£596

Wed 11/1106:15 -

2 stops23h 55m

Sun 15/1115:11 -

1 stop11h 24m

Deal found 29/9£846

Sat 21/1108:55 -

1 stop13h 23m

Sat 28/1113:05 -

1 stop12h 45m

Deal found 1/10£712

Thu 12/1107:30 -

2 stops22h 33m

Thu 19/1117:37 -

1 stop10h 48m

Deal found 28/9£864

Wed 28/1006:30 -

2 stops21h 03m

Sat 7/1110:12 -

1 stop14h 53m

Deal found 3/10£751

Thu 12/1120:15 -

2 stops32h 58m

Thu 19/1110:43 -

2 stops16h 02m

Deal found 28/9£947

Fri 13/1107:40 -

1 stop19h 33m

Fri 20/1117:30 -

1 stop30h 25m

Deal found 29/9£866

Wed 14/1006:40 -

1 stop15h 30m

Wed 21/1007:25 -

2 stops19h 55m

Deal found 1/10£660

Fri 20/1111:20 -

2 stops17h 34m

Mon 30/1109:30 -

2 stops15h 20m

Deal found 2/10£765

Sun 15/1111:05 -

2 stops35h 42m

Sun 22/1117:35 -

1 stop30h 20m

Deal found 1/10£803

Fri 23/1011:45 -

2 stops16h 48m

Wed 4/1113:27 -

2 stops13h 33m

Deal found 29/9£772

Find flight deals from Heathrow to Illinois

Round-trip from	£534
One-way from	£358
Popular in	August
Cheapest in	February
Average price	£625
Good round-trip deal	£593 or less
Good one-way deal	£573 or less

Icelandair
25/12-16/1
2 total stops
20h 30m total
London to Illinois

Search Deals

10/12-31/12
3 total stops
27h 30m total
London to Illinois

Search Deals

Highest demand for flights based on searches. 12% potential increase in price (£65 potential increase over avg. return price).

Search Deals

Cheapest flight prices on average. 2% potential price decrease (£11 potential savings vs. average return price).

Search Deals

Average for round-trip flights in October 2026

Search Deals

Price to beat on a round-trip flight from London Heathrow to Illinois.

Search Deals

Price to beat on a one-way flight from London Heathrow to Illinois.

Search Deals

Cheapflights Fare Finder

Use the filters below to find and compare flights from London Heathrow Airport to Illinois that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest return flight

LondonChicago

LHR London Heathrow - ORD Chicago O'Hare Intl

LHRORD

London Heathrow

Thu 12/11

14:50-14:00

1 stop29h 10m

Chicago O'Hare Intl

Wed 31/12

00:00-07:00

Nonstop0h 00m

£376

LondonChicago

LHR London Heathrow - ORD Chicago O'Hare Intl

LHRORD

London Heathrow

Fri 20/11

14:50-14:00

1 stop29h 10m

Chicago O'Hare Intl

Wed 31/12

00:00-07:00

Nonstop0h 00m

£391

LondonChicago

LHR London Heathrow - ORD Chicago O'Hare Intl

LHRORD

London Heathrow

Wed 2/12

10:25-13:45

Nonstop9h 20m

Chicago O'Hare Intl

Wed 31/12

00:00-07:00

Nonstop0h 00m

£414

LondonChicago

LHR London Heathrow - MDW Chicago Midway

LHRMDW

London Heathrow

Tue 1/12

06:30-18:01

2 stops17h 31m

Chicago Midway

Wed 31/12

00:00-07:00

Nonstop0h 00m

£417

LondonChicago

LHR London Heathrow - ORD Chicago O'Hare Intl

LHRORD

London Heathrow

Mon 30/11

13:00-09:01

2 stops26h 01m

Chicago O'Hare Intl

Wed 31/12

00:00-07:00

Nonstop0h 00m

£422

LondonChicago

LHR London Heathrow - MDW Chicago Midway

LHRMDW

London Heathrow

Wed 2/12

09:50-16:50

1 stop13h 00m

Chicago Midway

Wed 31/12

00:00-07:00

Nonstop0h 00m

£430

LondonChicago

LHR London Heathrow - MDW Chicago Midway

LHRMDW

London Heathrow

Wed 18/11

12:40-22:54

1 stop16h 14m

Chicago Midway

Wed 31/12

00:00-07:00

Nonstop0h 00m

£431

LondonChicago

LHR London Heathrow - ORD Chicago O'Hare Intl

LHRORD

London Heathrow

Wed 30/12

17:20-12:51

1 stop25h 31m

Chicago O'Hare Intl

Wed 31/12

00:00-07:00

Nonstop0h 00m

£440

LondonChicago

LHR London Heathrow - ORD Chicago O'Hare Intl

LHRORD

London Heathrow

Thu 3/12

10:25-13:45

Nonstop9h 20m

Chicago O'Hare Intl

Wed 31/12

00:00-07:00

Nonstop0h 00m

£456

Fastest return journey

LondonChicago

LHR London Heathrow - ORD Chicago O'Hare Intl

LHRORD

London Heathrow

Fri 27/11

07:40-10:45

Nonstop9h 05m

Chicago O'Hare Intl

Wed 31/12

00:00-07:00

Nonstop0h 00m

£456

Flights are sorted by cheapest return flights first.

Deals found on 28/9

Showing 1-10 of 53 resultsSorted by cheapest first

...

Best time to book a flight from Heathrow to Illinois

Have a flexible travel schedule? Discover the best time to fly to Illinois from Heathrow with our price prediction graph.

LHR-ORD

LHR-MDW

LHR-SPI

LHR-PIA

LHR-BMI

Estimated return price

Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from London Heathrow Airport to Illinois

LHR-USIL

LHR-ORD

LHR-MDW

LHR-SPI

LHR-PIA

What is the cheapest month to book a flight from London Heathrow Airport to Illinois?

Currently, February is the cheapest month in which you can book a flight from London Heathrow Airport to Illinois (average of £508). Flying from London Heathrow Airport to Illinois in August is currently the most expensive (average of £838). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from LHR to IL?

When flying from London Heathrow Airport to Illinois, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.

Weekly flight availability from London Heathrow Airport to Illinois

The most flights from LHR to USIL are scheduled on a Wednesday (50 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (29 on average).

How much does it cost for a return flight from London Heathrow Airport to Illinois?

Airfare is below average for this route at the moment.

London Heathrow Airport to Illinois flights typically cost between £605 and £798 in December.
The cheapest return price found within the last 5 days was £534 on Icelandair (25 Dec–16 Jan).

How far ahead should I book a flight from London Heathrow Airport to Illinois?

The price you pay for your flight from London Heathrow Airport to Illinois may vary depending on when you book. For the best chance of a lower fare, look to book 79 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

Reviews of airlines servicing Illinois

Read through reviews of airlines operating flights from London Heathrow Airport to Illinois, such as United Airlines,Aer Lingus, andIcelandair. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.

United Airlines

7.4

Good

10,280 reviews

Check prices

Reviews

1 / 20

4.0

Okay

Chris,Aug 2026

MIA - ORD

Had to go through TSA again, already purchased bottle drink. TSA would not let through, United changed gates last minute. This experience bad for everyone. Staff rude, not our fault. Staff from Chicago to Wichita excellent!

United Airlines

7.4

Good

10,280 reviews

United Airlines

7.4

Good

10,280 reviews

Check prices

Reviews

1 / 20

4.0

Okay

Chris,Aug 2026

MIA - ORD

Aer Lingus

7.3

Good

1,811 reviews

United Airlines

7.4

Good

10,280 reviews

Check prices

Reviews

1 / 20

4.0

Okay

Chris,Aug 2026

MIA - ORD

Icelandair

6.9

Okay

756 reviews

United Airlines

7.4

Good

10,280 reviews

Check prices

Reviews

1 / 20

4.0

Okay

Chris,Aug 2026

MIA - ORD

Lufthansa

6.8

Okay

8,253 reviews

United Airlines

7.4

Good

10,280 reviews

Check prices

Reviews

1 / 20

4.0

Okay

Chris,Aug 2026

MIA - ORD

British Airways

6.7

Okay

8,243 reviews

United Airlines

7.4

Good

10,280 reviews

Check prices

Reviews

1 / 20

4.0

Okay

Chris,Aug 2026

MIA - ORD

Related info for your journey

How long is the flight from London Heathrow Airport to Illinois?
Departing from London Heathrow Airport to Illinois will take you 9h 15m. The distance from London Heathrow Airport to Illinois is about 3939 mi. Both multi-stop and direct flights can be found to your destination and back.
What are the cheapest airlines to fly from London Heathrow Airport to Illinois one-way?
One-way options have recently been found by users for as low as £316 on JetBlue. Other airlines that offer cheap prices include Aer Lingus from £320 and Austrian Airlines from £328 one-way.
What are the most popular routes from London Heathrow Airport to Illinois?
The most popular flight routes from London Heathrow Airport to Illinois are London Heathrow - Chicago O'Hare Intl, London Heathrow - Chicago Midway and London Heathrow - Lambert-St Louis.
What are the most reliable airlines from London Heathrow Airport to Illinois?
Before booking your flight to Illinois from London Heathrow Airport, check out the most reliable airlines to get you to your destination on time: Air Canada (88%), Austrian Airlines (88%), United Airlines( 88%).
What are the cheapest flights from London Heathrow Airport to Illinois?
Looking at all options, your cheapest flight can be booked for £406. While the most popular route (London Heathrow - Chicago O'Hare Intl) can be booked for £377 on average, our data indicates £1,584 when flying from London Heathrow Airport to Illinois.
Can I find deals for flights from Heathrow to Illinois that include hotel bookings?
Yes. In addition to deals on Heathrow to Illinois flights, Cheapflights offers holiday packages that include both flights and hotel.
How can I find direct flights from Heathrow to Illinois?
After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Heathrow to Illinois.
Can I find deals for business class flights from Heathrow to Illinois?
Yes. Cheapflights offers flight deals from Heathrow to Illinois by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.
What is the cheapest month to book a flight from London Heathrow Airport to Illinois?
Currently, February is the cheapest month in which you can book a flight from London Heathrow Airport to Illinois (average of £508). Flying from London Heathrow Airport to Illinois in August is currently the most expensive (average of £838). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Browse thousands of different options on Cheapflights for your next trip

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Top destinations

Alternative routes for Heathrow to Illinois

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Gatwick to Newark flights

Stansted to John F Kennedy Intl flights

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Stansted to Miami flights

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Gatwick to Dallas/Fort Worth flights

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Stansted to Dallas/Fort Worth flights

Heathrow to Austin flights

Heathrow to Love Field flights

Stansted to Boston flights

London City to Dallas/Fort Worth flights

Heathrow to Tampa flights

Luton to Orlando flights

London City to San Francisco flights

Gatwick to Hobby flights

Top 10 airlines flying from Heathrow to Illinois

Airline	Cheapest	Average	Flexibility	On-time
Virgin Atlantic	Cheapest£215	Average£661	FlexibilityNo cancel fee	On-time72%	Search Virgin Atlantic flights
Icelandair	Cheapest£388	Average£516	FlexibilityNo cancel fee	On-time76%	Search Icelandair flights
JetBlue	Cheapest£389	Average£693	FlexibilityNo cancel fee	On-time62%	Search JetBlue flights
Scandinavian Airlines	Cheapest£392	Average£555	FlexibilityNo cancel fee	On-time77%	Search Scandinavian Airlines flights
TAP AIR PORTUGAL	Cheapest£393	Average£590	FlexibilityNo cancel fee	On-timeN/A	Search TAP AIR PORTUGAL flights
Brussels Airlines	Cheapest£412	Average£800	FlexibilityNo cancel fee	On-timeN/A	Search Brussels Airlines flights
British Airways	Cheapest£427	Average£701	FlexibilityNo cancel fee	On-time70%	Search British Airways flights
Finnair	Cheapest£435	Average£731	FlexibilityNo cancel fee	On-time76%	Search Finnair flights
United Airlines	Cheapest£437	Average£778	FlexibilityNo cancel fee	On-time69%	Search United Airlines flights
American Airlines	Cheapest£440	Average£792	FlexibilityNo cancel fee	On-time71%	Search American Airlines flights

Fly with Cheapflights

How does Cheapflights help users find flights from Heathrow to Illinois?

Cheapflights helps you search for flights from Heathrow to Illinois via 900+ travel sites so you don’t have to. After performing a flight search, users can also filter their flight selection by filtering for price, number of stops, airlines, and so on.

Why should you use Cheapflights to find cheap flight tickets from Heathrow to Illinois?

Cheapflights taps into our reliable network of hundreds of airlines and travel agencies to find the best deals for flights from Heathrow to Illinois for you. Better yet — we are completely free to use.

Can Cheapflights find flights from Heathrow to Illinois with no change fees?

Yes! Cheapflights helps users easily find flights from Heathrow to Illinois with no change fees.

Can Cheapflights notify me if prices for flights from Heathrow to Illinois become cheaper?

Of course! You can now track prices for flights from Heathrow to Illinois and get an alert from Cheapflights when they change. Have a valid email address ready and click the bell icon next to the flight deals above to set up your price alerts.

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Cheap flights from London Heathrow Airport to Illinois from £358

This is the cheapest retur flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 10/12. Fares are subject to change and may not be available on all flights or dates of travel.

Cheap flight deals from Heathrow to Illinois

Cheapest flights from Heathrow to IllinoisExplore the most affordable flight options available from Heathrow to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 3 October 2026.

Explore the most affordable flight options available from Heathrow to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 3 October 2026.

Best flights from Heathrow to IllinoisDiscover carefully curated flight deals from Heathrow to Illinois that have cost, travel time, and stopovers in mind to ensure you get the best travel experience. Data last updated 3 October 2026.

Discover carefully curated flight deals from Heathrow to Illinois that have cost, travel time, and stopovers in mind to ensure you get the best travel experience. Data last updated 3 October 2026.

Direct flights from Heathrow to IllinoisExplore direct flight options from Heathrow to Illinois based on user searches, and compare prices and availability for your desired travel dates. Data last updated 3 October 2026.

Explore direct flight options from Heathrow to Illinois based on user searches, and compare prices and availability for your desired travel dates. Data last updated 3 October 2026.

Last-minute flights from Heathrow to IllinoisDiscover last-minute flight deals from Heathrow to Illinois. Data last updated 3 October 2026 and is based on user searches.

Discover last-minute flight deals from Heathrow to Illinois. Data last updated 3 October 2026 and is based on user searches.

One-way flights from Heathrow to IllinoisSearch for one-way flight options from Heathrow to Illinois. Find affordable one-way fares based on user searches. Data last updated 3 October 2026.

Search for one-way flight options from Heathrow to Illinois. Find affordable one-way fares based on user searches. Data last updated 3 October 2026.

Find flight deals from Heathrow to Illinois

Round-trip from

One-way from

Popular in

Cheapest in

Average price

Good round-trip deal

Good one-way deal

Cheapflights Fare Finder

Use the filters below to find and compare flights from London Heathrow Airport to Illinois that are best for you.

Best time to book a flight from Heathrow to Illinois

Have a flexible travel schedule? Discover the best time to fly to Illinois from Heathrow with our price prediction graph.

Cheapflights Insights

What is the cheapest month to book a flight from London Heathrow Airport to Illinois?

What is the cheapest time of day to fly from LHR to IL?

Find hourly flight availability from Heathrow to Illinois. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated 3 October 2026.

When flying from London Heathrow Airport to Illinois, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.

Weekly flight availability from London Heathrow Airport to Illinois

Explore weekly flight availability from Heathrow to Illinois. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated 3 October 2026.

The most flights from LHR to USIL are scheduled on a Wednesday (50 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (29 on average).

How much does it cost for a return flight from London Heathrow Airport to Illinois?

Airfare is below average for this route at the moment.

London Heathrow Airport to Illinois flights typically cost between £605 and £798 in December.The cheapest return price found within the last 5 days was £534 on Icelandair (25 Dec–16 Jan).

How far ahead should I book a flight from London Heathrow Airport to Illinois?

The price you pay for your flight from London Heathrow Airport to Illinois may vary depending on when you book. For the best chance of a lower fare, look to book 79 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

Reviews of airlines servicing Illinois

Read through reviews of airlines operating flights from London Heathrow Airport to Illinois, such as United Airlines,Aer Lingus, andIcelandair. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.

Related info for your journey

How long is the flight from London Heathrow Airport to Illinois?

What are the cheapest airlines to fly from London Heathrow Airport to Illinois one-way?

What are the most popular routes from London Heathrow Airport to Illinois?

What are the most reliable airlines from London Heathrow Airport to Illinois?

What are the cheapest flights from London Heathrow Airport to Illinois?

Can I find deals for flights from Heathrow to Illinois that include hotel bookings?

How can I find direct flights from Heathrow to Illinois?

Can I find deals for business class flights from Heathrow to Illinois?

What is the cheapest month to book a flight from London Heathrow Airport to Illinois?

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Heathrow to Illinois

See prices for flight routes from nearby airports that may be better suited for you.

Complete your trip

Complete your trip to Illinois by adding a car hire and/or hotel booking to your travel itinerary.

Direct flights to United States

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Heathrow and Illinois flights

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Heathrow to Illinois flights

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Cheapest flights from Heathrow to Illinois
Explore the most affordable flight options available from Heathrow to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 3 October 2026.

Best flights from Heathrow to Illinois
Discover carefully curated flight deals from Heathrow to Illinois that have cost, travel time, and stopovers in mind to ensure you get the best travel experience. Data last updated 3 October 2026.

Direct flights from Heathrow to Illinois
Explore direct flight options from Heathrow to Illinois based on user searches, and compare prices and availability for your desired travel dates. Data last updated 3 October 2026.

Last-minute flights from Heathrow to Illinois
Discover last-minute flight deals from Heathrow to Illinois. Data last updated 3 October 2026 and is based on user searches.

One-way flights from Heathrow to Illinois
Search for one-way flight options from Heathrow to Illinois. Find affordable one-way fares based on user searches. Data last updated 3 October 2026.

London Heathrow Airport to Illinois flights typically cost between £605 and £798 in December.
The cheapest return price found within the last 5 days was £534 on Icelandair (25 Dec–16 Jan).