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Cheap flights from Illinois to Sydney from $650

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 14/4. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — SYD
29 Mar — 5 Apr1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from Illinois to Sydney

Enter your travel dates to find the best prices.

Cheapest flights from Illinois to Sydney
Explore the most affordable flight options available from Illinois to Sydney. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 27 February 2026.

Sat 28/206:38
STL
-
SYD
2 stops33h 42m
Qantas Airways
Mon 2/314:05
SYD
-
STL
1 stop22h 24m
Qantas Airways
Deal found 24/2$1,520
Tue 28/406:20
ORD
-
SYD
2 stops38h 30m
Multiple Airlines
Tue 12/517:50
SYD
-
ORD
1 stop27h 00m
Multiple Airlines
Deal found 24/2$1,521
Tue 28/406:20
ORD
-
SYD
2 stops38h 30m
Multiple Airlines
Mon 11/517:50
SYD
-
ORD
1 stop27h 00m
Multiple Airlines
Deal found 24/2$1,523
Fri 10/406:21
STL
-
SYD
2 stops35h 59m
Qantas Airways
Fri 17/412:00
SYD
-
STL
1 stop20h 21m
Qantas Airways
Deal found 25/2$1,528
Tue 28/406:20
ORD
-
SYD
2 stops38h 30m
Multiple Airlines
Thu 14/517:50
SYD
-
ORD
1 stop27h 00m
Multiple Airlines
Deal found 24/2$1,531
Tue 28/406:20
ORD
-
SYD
2 stops38h 30m
Multiple Airlines
Wed 13/517:50
SYD
-
ORD
1 stop27h 00m
Multiple Airlines
Deal found 24/2$1,532
Sat 7/311:46
STL
-
SYD
1 stop26h 09m
Qantas Airways
Sat 14/311:30
SYD
-
STL
2 stops28h 28m
Qantas Airways
Deal found 25/2$1,532
Sat 26/1215:30
STL
-
SYD
2 stops26h 25m
Qantas Airways
Sat 16/114:05
SYD
-
STL
1 stop19h 09m
Qantas Airways
Deal found 27/2$1,537
Tue 28/406:20
ORD
-
SYD
2 stops38h 30m
Multiple Airlines
Sun 10/517:50
SYD
-
ORD
1 stop27h 00m
Multiple Airlines
Deal found 24/2$1,538
Tue 13/1018:04
STL
-
SYD
1 stop20h 51m
Qantas Airways
Fri 13/1106:00
SYD
-
STL
2 stops23h 37m
Qantas Airways
Deal found 24/2$1,539
Sat 2/506:21
STL
-
SYD
2 stops38h 34m
Qantas Airways
Sat 16/512:00
SYD
-
STL
1 stop20h 21m
Qantas Airways
Deal found 25/2$1,541
Mon 4/506:21
STL
-
SYD
2 stops38h 34m
Qantas Airways
Mon 18/512:00
SYD
-
STL
1 stop22h 30m
Qantas Airways
Deal found 24/2$1,542

Find flight deals from Illinois to Sydney

Keep the following information in mind while searching for Illinois to Sydney flight deals. Data was last updated 27 February 2026.

Round-trip from

$1,521

One-way from

$650

Popular in

December

Cheapest in

October

Average price

$1,542
28/4-12/5
  • 28/4-12/5
  • 3 total stops
  • 65h 30m total
  • Illinois to Sydney
Search Deals
14/4
  • 14/4
  • 2 total stops
  • 29h 23m total
  • Illinois to Sydney
Search Deals
Highest demand for flights based on searches. 9% potential increase in price ($274 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 1% potential price decrease ($47 potential savings vs. average return price).
Search Deals
Average for round-trip flights in February 2026
Search Deals

Cheapflights Fare Finder

 
Customise your flight search to find flights from Illinois to Sydney that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 647,157 searches. Data last updated 27 February 2026.
Use the filters below to find and compare flights from Illinois to Sydney that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

St. LouisSydney

STL - SYD

STLSYD

Lambert-St Louis

Mon 4/5

19:06-06:55

1 stop20h 49m

Sydney Kingsford Smith

Mon 18/5

10:20-18:22

1 stop23h 02m

$1,591

St. LouisSydney

STL - SYD

STLSYD

Lambert-St Louis

Sat 23/5

19:05-06:50

2 stops44h 45m

Sydney Kingsford Smith

Tue 9/6

09:15-16:45

2 stops22h 30m

$1,598

St. LouisSydney

STL - SYD

STLSYD

Lambert-St Louis

Mon 4/5

09:59-06:50

2 stops29h 51m

Sydney Kingsford Smith

Mon 18/5

09:15-17:56

2 stops23h 41m

$1,615

St. LouisSydney

STL - SYD

STLSYD

Lambert-St Louis

Wed 27/5

19:23-06:55

1 stop20h 32m

Sydney Kingsford Smith

Wed 10/6

09:30-21:16

2 stops26h 46m

$1,615

St. LouisSydney

STL - SYD

STLSYD

Lambert-St Louis

Wed 18/3

13:39-07:25

2 stops25h 46m

Sydney Kingsford Smith

Wed 25/3

09:40-16:32

2 stops22h 52m

$1,615

St. LouisSydney

STL - SYD

STLSYD

Lambert-St Louis

Wed 20/5

19:06-06:55

1 stop20h 49m

Sydney Kingsford Smith

Mon 8/6

10:20-23:57

2 stops28h 37m

$1,615

St. LouisSydney

STL - SYD

STLSYD

Lambert-St Louis

Sun 24/5

17:00-06:50

2 stops22h 50m

Sydney Kingsford Smith

Sat 6/6

09:15-21:06

2 stops26h 51m

$1,656

St. LouisSydney

STL - SYD

STLSYD

Lambert-St Louis

Sat 1/8

10:45-06:50

2 stops29h 05m

Sydney Kingsford Smith

Sun 9/8

09:15-20:31

2 stops26h 16m

$1,673

St. LouisSydney

STL - SYD

STLSYD

Lambert-St Louis

Sat 2/5

08:30-06:55

1 stop31h 25m

Sydney Kingsford Smith

Sat 16/5

10:20-18:22

1 stop23h 02m

$1,705

St. LouisSydney

STL - SYD

STLSYD

Lambert-St Louis

Sat 16/5

16:44-07:00

2 stops23h 16m

Sydney Kingsford Smith

Sat 23/5

10:20-18:17

1 stop22h 57m

$1,722

Flights are sorted by cheapest return flights first.

Deals found on 27/2

Showing 1-10 of 55 resultsSorted by cheapest first
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Best time to book a flight from Illinois to Sydney

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

What is the cheapest month to book a flight from Illinois to Sydney?

Currently, August is the cheapest month in which you can book a flight from Illinois to Sydney (average of $278). Flying from Illinois to Sydney in October is currently the most expensive (average of $1,224). 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.

Related info for your journey

Find useful and relevant information for your journey from Illinois to Sydney. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly into for flights to Sydney from Illinois?

    Located just 7.5 km from the city centre, Sydney Kingsford Smith (SYD) is the airport most travelers will use when flying to Sydney from Illinois.

  • How long is the flight from Illinois to Sydney?

    A quick flight from Illinois to Sydney can take about 20h 49m. United Airlines provides one of the quickest options available for as low as $1,591. The distance between Illinois and Sydney is about 14571 km. Both multi-stop and direct flights can be found to your destination and back.

  • What are the most popular routes from Illinois to Sydney?

    When deciding which route to take from Illinois to Sydney, consider Chicago O'Hare Intl - Sydney Kingsford Smith, Chicago Midway - Sydney Kingsford Smith or Lambert-St Louis - Sydney Kingsford Smith, as they are the most popular.

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

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

  • How can I find direct flights from Illinois to Sydney?

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

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

    Yes. Cheapflights offers flight deals from Illinois to Sydney 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 Illinois to Sydney?

    Currently, August is the cheapest month in which you can book a flight from Illinois to Sydney (average of $278). Flying from Illinois to Sydney in October is currently the most expensive (average of $1,224). 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

Travelling to a place near Sydney?

Book flights to Sydney if you plan to visit one of these locations
Parramatta
Wollongong
Penrith
Katoomba
Manly
Terrigal
Lithgow
Bondi Beach
Leura
Coogee
Cronulla
Randwick

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.

Top airline flying from Illinois to Sydney

Discover the top airline that operate flights from Illinois to Sydney. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 647,157 searches. Data last updated 27 February 2026.
AirlineCheapestAverageFlexibilityOn-time
Qantas AirwaysCheapest$1,902Average$2,287FlexibilityNo cancel feeOn-time74%
Search Qantas Airways flights

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travellers can enjoy low prices and a wide availability of flights to their desired destinations.

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

When you search for this flight from Illinois to Sydney, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

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

Millions of users choose and trust Cheapflights to book the best flight deals from Illinois to Sydney for free. We help you search and compare prices from hundreds of airlines for the right flight just for you.

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

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

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

Of course! You can now track prices for flights from Illinois to Sydney 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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